Engineering English
1 Gear /ɡɪər/ Dişli çark
A rotating machine element with cut teeth that mesh with another toothed part to transmit torque and change the speed or direction of motion.
Mechanical Engineering Terms in English
Mechanical Engineering English covers terms for machines, mechanisms, thermodynamics and fluid power — gears, bearings, torque, heat transfer and everything that moves. This free glossary lists the 60 most frequently used of the 500 Mechanical Engineering terms in the Engineering English iOS app — each with IPA pronunciation and a working definition. In the app, every term also includes example sentences, translations in 21 languages, flashcards and AI conversation practice.
Machine datasheets, maintenance manuals and CAD documentation are overwhelmingly written in English. From reading a pump curve to explaining a bearing failure to an international supplier, mechanical engineers use this vocabulary daily in global teams.
Last updated: July 30, 2026 · How terms are selected and ranked · 🇹🇷 Türkçesi
Quick answer: The 10 most frequently used Mechanical Engineering terms in English are Gear, Bearing, Bolt, Timing Belt, Roller Chain, Gear Ratio, Pressure Drop, Pressure Relief Valve, Flow Rate, Nominal Pipe Size (NPS). The full Engineering English library contains 500 Mechanical Engineering terms with pronunciation, example sentences, translations and flashcards.
The 60 most-used Mechanical Engineering terms, ranked by frequency
2 Bearing /ˈbɛərɪŋ/ Rulman
A machine element that supports a rotating or sliding shaft, constrains its motion, and reduces friction between moving parts.
3 Bolt /bəʊlt/ Cıvata
An externally threaded fastener designed to pass through aligned holes and be tightened with a nut to clamp parts together.
4 Timing Belt /ˈtaɪmɪŋ bɛlt/ Triger kayışı
A timing belt is a toothed belt that synchronizes the rotation of the crankshaft and camshaft in an internal combustion engine, or maintains precise positional alignment between two rotating shafts in machinery.
5 Roller Chain /ˈroʊlər tʃeɪn/ Makara zinciri
A roller chain is a power transmission chain consisting of alternating roller and pin links that engage with sprocket teeth, providing efficient and positive drive in applications such as conveyors and motorcycles.
6 Gear Ratio /ɡɪr ˈreɪʃioʊ/ Dişli oranı
The gear ratio is the ratio of the number of teeth on two meshing gears, or the ratio of input to output speeds in a gear train. It determines torque multiplication and speed reduction.
7 Pressure Drop /ˈprɛʃər drɒp/ Basınç düşüşü
Pressure drop is the decrease in static pressure of a fluid as it flows through a pipe, valve, or fitting due to friction and changes in flow area.
8 Pressure Relief Valve /ˈprɛʃər rɪˈliːf vælv/ Emniyet ventili
A pressure relief valve is a safety device that automatically releases fluid from a system when the pressure exceeds a preset limit to prevent overpressure conditions.
9 Flow Rate /ˈfloʊ reɪt/ Debi
Flow rate is the volume or mass of fluid passing through a cross-section per unit time. It is a fundamental parameter in fluid system design and analysis.
10 Nominal Pipe Size (NPS) /ˈnɒmɪnəl paɪp saɪz/ Nominal Boru Boyutu (NPS)
A dimensionless designator that corresponds to the diameter of a pipe, not equal to the actual outside diameter. It is used to standardize pipe dimensions across different schedules and materials.
11 Rankine Cycle /ˈræŋkɪn ˈsaɪkəl/ Rankine çevrimi
A thermodynamic cycle that converts heat into mechanical work, commonly used in steam power plants. It involves four steps: isentropic compression, constant-pressure heat addition, isentropic expansion, and constant-pressure heat rejection.
12 Brayton Cycle /ˈbreɪtən ˈsaɪkəl/ Brayton çevrimi
A thermodynamic cycle that describes the workings of a gas turbine engine. It consists of isentropic compression, constant-pressure heat addition, isentropic expansion, and constant-pressure heat rejection.
13 Otto Cycle /ˈɒtoʊ ˈsaɪkəl/ Otto çevrimi
An ideal thermodynamic cycle that models the operation of a spark-ignition internal combustion engine. It includes isentropic compression, constant-volume heat addition, isentropic expansion, and constant-volume heat rejection.
14 Diesel Cycle /ˈdiːzəl ˈsaɪkəl/ Dizel çevrimi
A thermodynamic cycle that models a compression-ignition internal combustion engine. It differs from the Otto cycle by having constant-pressure heat addition instead of constant-volume heat addition.
15 Carnot Cycle /ˈkɑːrnoʊ ˈsaɪkəl/ Carnot çevrimi
An idealized thermodynamic cycle that provides the maximum possible efficiency for a heat engine operating between two thermal reservoirs. It consists of two isothermal processes and two adiabatic processes.
16 Isentropic Efficiency /aɪsɛnˈtrɒpɪk ɪˈfɪʃənsi/ İzentropik verim
Isentropic efficiency is the ratio of the actual work output or input of a device to the work that would be produced or required if the process were reversible and adiabatic. It quantifies how closely a real compressor, turbine, or nozzle approaches the ideal isentropic process.
17 Compression Ratio /kəmˈprɛʃən ˈreɪʃioʊ/ Sıkıştırma oranı
Compression ratio is the ratio of the maximum volume of a cylinder to the minimum volume when the piston is at top dead center. It directly affects the thermal efficiency of internal combustion engines and is critical for performance and knock resistance.
18 Refrigerant /rɪˈfrɪdʒərənt/ Soğutucu akışkan
A substance used as the working fluid in a refrigeration cycle that absorbs and releases heat through phase changes, typically evaporation and condensation. It circulates through the system to transfer thermal energy.
19 Vapor Compression Cycle /ˈveɪpər kəmˈprɛʃən ˈsaɪkəl/ Buhar Sıkıştırmalı Çevrim
A thermodynamic cycle used in refrigeration and air conditioning systems where a refrigerant alternately evaporates and condenses by compressing and expanding. It transfers heat from a low-temperature reservoir to a high-temperature reservoir with work input.
20 Bore /bɔr/ Silindir çapı
Bore is the inner diameter of an engine cylinder. It determines the cross-sectional area of the combustion chamber and is a key variable in engine displacement and power calculations.
21 Octane Rating /ˈɑkteɪn ˈreɪtɪŋ/ Oktan sayısı
Octane rating is a measure of a fuel's ability to resist detonation (knock) in a spark-ignition internal combustion engine. Higher numbers indicate greater resistance to auto-ignition.
22 Cylinder Head /sɪlɪndər hɛd/ Silindir kapağı
The cylinder head covers the top of the engine block and contains the combustion chambers, valves, and spark plug or injector ports. It forms the upper seal for the cylinders and houses the valve train components.
23 Engine Block /ɛndʒɪn blɑk/ Motor bloğu
The engine block is the main structural component of an internal combustion engine that houses the cylinders, crankshaft, and often the camshaft. It provides mounting points for other engine parts and contains coolant and oil passages.
24 ECU /ˌiː siː ˈjuː/ Motor kontrol ünitesi (ECU)
An electronic module that manages engine functions such as ignition timing, fuel injection, and variable valve timing based on sensor inputs.
25 Torque /tɔːk/ Tork
Torque is the rotational equivalent of linear force, measuring the twisting effort produced by an engine's crankshaft. It is typically expressed in newton-meters or pound-feet.
26 Horsepower /hɔːrsˌpaʊər/ Beygir gücü
Horsepower is a unit of power that measures the rate at which an engine performs work, commonly used to rate engine output in vehicles and machinery. One horsepower equals 550 foot-pounds per second or approximately 746 watts.
27 Link /lɪŋk/ Bağlantı elemanı
A link is a rigid body in a mechanism that is connected to other links through joints, forming a kinematic chain. It transmits motion or force from one part of the mechanism to another.
28 Pin Joint /pɪn dʒɔɪnt/ Pimli eklem
A kinematic pair that permits only relative rotation between two rigid links about a common axis. It is a single-degree-of-freedom joint commonly used in linkages, trusses, and mechanical assemblies to allow smooth pivoting.
29 Yield Strength /ˈjiːld strɛŋkθ/ Akma Dayanımı
The stress at which a material begins to deform plastically. Beyond this point, the material will not return to its original shape.
30 Von Mises Stress /vɒn ˈmiːzɪs stɹɛs/ Von Mises gerilmesi
Von Mises stress is a scalar value calculated from the deviatoric component of the stress tensor, used as a criterion to predict yielding in ductile materials under multiaxial loading. It is often employed in finite element analysis to assess whether a material point will fail.
31 Strain /streɪn/ Gerinme
The ratio of change in length to original length of a material under load. It is a dimensionless measure of deformation.
32 Fatigue /fəˈtiːɡ/ Yorulma
The progressive and localized structural damage that occurs when a material is subjected to cyclic loading. It leads to crack initiation and growth, potentially causing failure.
33 Stress /stres/ Gerilme
The internal force per unit area within a material that arises from externally applied loads. It is measured in pascals and is fundamental in determining material strength.
34 Natural Frequency /ˈnætʃəɹəl ˈfɹiːkwənsi/ Doğal frekans
The natural frequency is the frequency at which a system oscillates when disturbed from its equilibrium position and left to vibrate freely. It is determined by the system's mass and stiffness distribution.
35 Rotor Imbalance /ˈroʊtər ɪmˈbæləns/ Rotor dengesizliği
Rotor imbalance refers to a condition where the mass distribution of a rotating component is not uniform around its axis of rotation. This causes centrifugal forces that generate vibration and can lead to premature bearing or shaft failure.
36 Resonant Frequency /ˈrɛzənənt ˈfrikwənsi/ Rezonans frekansı
Resonant frequency is the natural frequency at which a system vibrates with maximum amplitude when excited. In mechanical systems, operating near this frequency can cause large oscillations and potential structural failure.
37 Vibration Monitoring /vaɪˈbreɪʃən ˈmɑnɪtərɪŋ/ Titreşim izleme
Vibration monitoring is the continuous or periodic measurement of vibration levels in machinery to detect changes that indicate developing faults. It is a key predictive maintenance technique for rotating equipment.
38 Frequency Response Function /ˈfriːkwənsi rɪˈspɒns ˈfʌŋkʃən/ Frekans cevap fonksiyonu
A frequency response function is a mathematical representation of how a system responds to an input excitation at different frequencies. It is typically expressed as a complex ratio of output to input in the frequency domain.
39 Vibration Severity /vaɪˈbreɪʃən sɪˈvɛrɪti/ Titreşim şiddeti
Vibration severity is a measure of the intensity of vibration on a machine, often expressed as overall RMS velocity or displacement over a frequency range. It is used for condition monitoring and to compare against standards like ISO 10816.
40 Impeller /ɪmˈpɛlər/ Çark
The rotating component of a pump, compressor, or fan that transfers energy from the motor to the fluid by accelerating it outward radially or axially.
41 Pressure Ratio /ˈprɛʃər ˈreɪʃioʊ/ Basınç Oranı
Pressure ratio is the ratio of the absolute discharge pressure to the absolute suction pressure in a compressor or pump. It is a key parameter for determining the work required and the stage configuration.
42 Thermodynamics /ˌθɜːrmoʊdaɪˈnæmɪks/ Termodinamik
The branch of physical science that studies the relationships between heat, work, temperature, and energy in physical systems. It provides the laws governing energy conversion and the direction of spontaneous processes.
43 Heat Transfer /ˈhiːt ˌtrænsfɜːr/ Isı transferi
The movement of thermal energy from a region of higher temperature to one of lower temperature, occurring by conduction, convection, or radiation. Its rate depends on temperature difference, material properties, and surface geometry.
44 Pump /pʌmp/ Pompa
A machine that adds energy to a liquid in order to move it and to overcome elevation, friction, and pressure differences in a piping system. Centrifugal and positive displacement designs cover most industrial duties.
45 Gearbox /ˈɡɪəbɒks/ Dişli kutusu
An enclosed assembly of gears and shafts that transmits mechanical power while changing the torque and rotational speed between a driving and a driven machine.
46 Shaft /ʃɑːft/ Mil
A rotating machine element, usually of circular cross section, that transmits power and torque from one component to another.
47 Piston /ˈpɪstən/ Piston
A cylindrical component that moves back and forth inside a cylinder, transmitting force between a fluid and a connecting rod or shaft.
48 Cylinder /ˈsɪlɪndər/ Silindir
A chamber with a circular cross section in which a piston moves to compress or expand a fluid and convert energy into mechanical work.
49 Valve /vælv/ Valf
A device that regulates, directs, or blocks the flow of a fluid by opening, closing, or partially obstructing a passage.
50 Spring /sprɪŋ/ Yay
An elastic machine element that deforms under load and returns to its original shape, storing and releasing mechanical energy.
51 Nut /nʌt/ Somun
An internally threaded fastener that screws onto a bolt or stud to clamp assembled parts together.
52 Machine Design /məˈʃiːn dɪˈzaɪn/ Makine Tasarımı
The engineering process of creating, sizing, and specifying mechanical components and systems so they perform their intended function safely and economically.
53 Shear Stress /ˈʃɪr strɛs/ Kayma Gerilmesi
The internal stress component acting parallel to a material's cross section, produced when adjacent layers of material tend to slide past each other.
54 Bending Stress /ˈbɛndɪŋ strɛs/ Eğilme Gerilmesi
The normal stress developed in a beam or member when a bending moment curves it, producing tension on one side of the neutral axis and compression on the other.
55 Factor of Safety /ˈfæktər əv ˈseɪfti/ Emniyet Katsayısı
The ratio of a component's failure strength to the maximum expected working stress, used to cover uncertainties in loads, materials, and analysis.
56 Finite Element Analysis /ˈfaɪnaɪt ˈɛləmənt əˈnæləsɪs/ Sonlu Elemanlar Analizi
A numerical simulation method that divides a structure into small interconnected elements and solves the governing equations to approximate stresses, deformations, temperatures, or vibrations.
57 Lubrication /ˌluːbrɪˈkeɪʃən/ Yağlama
The introduction of a substance such as oil or grease between contacting surfaces to reduce friction, carry away heat, and protect against wear.
58 Preventive Maintenance /prɪˈvɛntɪv ˈmeɪntənəns/ Önleyici Bakım
A planned program of inspections, servicing and part replacement performed at fixed intervals while equipment is still working. Its purpose is to reduce the probability of unexpected breakdowns rather than to repair existing faults.
59 Troubleshooting /ˈtrʌbəlˌʃuːtɪŋ/ Arıza giderme
The systematic process of locating the cause of a malfunction in a machine or system by testing, observing symptoms and eliminating possibilities step by step. It ends when the faulty component or condition has been identified and corrected.
60 Actuator /ˈæktʃueɪtər/ Aktüatör
A device that converts an input energy signal, typically electrical, hydraulic or pneumatic, into controlled mechanical motion or force. It is the element of a control system that physically moves or regulates a mechanism.
Mechanical Engineering terms — frequently asked questions
What are the most common Mechanical Engineering terms in English?
The 10 most frequently used Mechanical Engineering terms in the Engineering English library are Gear, Bearing, Bolt, Timing Belt, Roller Chain, Gear Ratio, Pressure Drop, Pressure Relief Valve, Flow Rate, Nominal Pipe Size (NPS). This page lists the top 60 of 500 terms, ranked by usage frequency.
How many Mechanical Engineering terms are in the Engineering English app?
500. Each one includes an IPA pronunciation, a plain-English definition, a real example sentence and translations in 21 languages; the 60 most frequent are free to browse on this page.
How do you pronounce Mechanical Engineering terms in English?
Every term on this page shows its IPA transcription — for example Gear is pronounced /ɡɪər/, Bearing is /ˈbɛərɪŋ/ and Bolt is /bəʊlt/. The Engineering English app also plays audio for each term and checks your pronunciation with speech recognition.
440 more Mechanical Engineering terms in the app
Get every term with example sentences, audio, 21-language translations, flashcards and AI practice.
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