| a | anode | 
| ad | parted (divided) anode | 
| A | Ampere (quantity of electric current) | 
| Å | Angstrom (wavelength 10-8 cm) | 
| A1 | telegraphic operation | 
| A3 | telephone operation | 
| AVC | automatic gain control (AGC) | 
| b | base (category 16, 17) | 
| bs | tube for driver stage in amplifier, working in class B | 
| B | photocell sensitive to white light (category 14) | 
| B | cathode-ray tube with white luminescent screen (category 13) | 
| Bp | overloading immunity of crystal diodes | 
| c | collector (class 16, 17) | 
| c/s | cycle per second, Hertz | 
| C | capacity | 
| °C | degrees Celsius | 
| Ca1a2 | capacity between anodes of first and second diode | 
| Ca1a3 | capacity between anodes of first and third diode | 
| Ca1k | capacity between anode of first diode and cathode (or filament) | 
| Ca2a3 | capacity between anodes of second and third diode | 
| Ca2k | capacity between anode of second diode and cathode (or filament) | 
| Ca3k | capacity between anode of third diode and cathode (or filament) | 
| Ca4k | capacity between anode of fourth diode and cathode (or filament) | 
| Cag | capacity between anode and first grid | 
| Cag2 | capacity between anode and second grid | 
| Cag3 | capacity between anode and third grid | 
| Cak | capacity between anode and cathode (or filament) | 
| Cb | capacity of base | 
| Cb1 | capacity of base 1 | 
| Cb2 | capacity of base 2 | 
| Ckd | capacity between anode of diode and cathode (in combined tubes) | 
| Cfk | capacity between filament and cathode | 
| Cg1g2 | capacity between first and second grid | 
| Cg2k | capacity between second grid and cathode | 
| Cg3k | capacity between third grid and cathode | 
| Cgk | capacity between grid and cathode | 
| Cv | input capacity | 
| Cvs | output capacity | 
| Cvst | input capacity of filter for suppression of ripple | 
| Č | photocell sensitive to red light (category 14) | 
| d | total distortion [%] | 
| dB | decibel | 
| det | detection | 
| det/a | anode detection | 
| det/g | grid detection | 
| dis | discriminator | 
| D | diode | 
| D | penetrance | 
| ef | root-mean-square value, RMS | 
| em | emitter (category 16, 17) | 
| es | electrostatic (deflection, focusing) | 
| Em | tube for measuring purpose | 
| Epp | tube for intermittent duty | 
| Es | combined tube | 
| Esv | beam tetrode | 
| ES | mixer tube | 
| ES+osc | mixer tube with oscillator | 
| Ešp | tube for amplifier with wide bandwidth | 
| Etp | tube for unintermittent duty | 
| f | filament | 
| f | frequency | 
| f50% | frequency, in which operational values may reach 50 % of limit values. | 
| f75% | frequency, in which operational values may reach 75 % of limit values. | 
| f100% | frequency, in which operational values may reach 100 % of limit values. | 
| ff | tube with two filaments | 
| fff | tube with three filaments | 
| fm | frequency modulation | 
| fmax | maximal frequency | 
| fmin max | frequency range | 
| F | Farad (unity of capacity) | 
| g | grid | 
| g1 | first grid | 
| g2 | second grid | 
| g2+a | second grid connected to anode | 
| g3 | third grid | 
| g3+a | third grid connected to anode | 
| g4 | fourth grid | 
| g5 | fifth grid | 
| g6 | sixth grid | 
| G | power gain | 
| Gc/s | gigacycle per second (109 c/s, giga Hertz) | 
| Ge | germanium | 
| H | cathode-ray tube with brown luminescent screen (category 13) | 
| ind | indicator | 
| ind 1 | the first indication part | 
| ind 2 | the second indication part | 
| inf | photocell sensitive to infra-red light | 
| ip | value in pulse operation | 
| Ia | anode current | 
| Ia0 | quiescent current (without excitation) | 
| Ia max | maximal anode current | 
| Ia max = | maximal rectified anode current | 
| Iap | average anode current | 
| Ia sig max | anode current on maximum signal | 
| Ia vh | limit peak anode current | 
| Iaz vh | limit peak reverse anode current | 
| Ib1 | current of base 1 | 
| Ib2 | current of base 2 | 
| Ic | collector current | 
| Id | diode current (on diodes in combined tubes only) | 
| Id vh | limit peak diode current (on diodes in combined tubes only) | 
| Idz vh | limit peak reverse diode current (on diodes in combined tubes only) | 
| Iem | emitter current | 
| If | filament current | 
| If max | maximal filament current | 
| Ig1 | current of first grid | 
| Ig2 | current of second grid | 
| Ig2 sig max | current of second grid on maximal signal | 
| Ig3 | current of third grid | 
| Ig3g5 | current of third and fifth grid | 
| Ig4 | current of fourth grid | 
| Ig max | maximal current of grid | 
| Igo | grid current in oscillator | 
| Ig vh | limit peak grid current | 
| Ik | cathode current | 
| Ik2 | secondary emissive current | 
| Ike | emissive cathode current | 
| Ik max | maximal cathode current | 
| Ik vh | limit peak cathode current | 
| Imax | maximal current | 
| Imax 1 | limit current in maximal duration 1 minute | 
| Imin | minimum current | 
| Imin max | current range | 
| Ip imp | limit pulse current in forward direction | 
| Ip min | minimum forward current on voltage 1 V | 
| Ip stř | limit average current in forward direction | 
| Iss | maximal rectified current | 
| Ist | screen current | 
| Itd | current in heating wire, whereat originate electromotive force 12 mV | 
| Izb | residual current (category 16, 17) | 
| Iz max | maximal reverse current for specific voltage | 
| k | cathode | 
| kc/s | kilocycle per second (103 c/s, kilo Hertz) | 
| ke | ceramics | 
| kv | metal | 
| kV | kilo Volt (103 V) | 
| kW | kilo Watt (103 W) | 
| kΩ | kilo Ω | 
| K | amplification (factor) | 
| Kv | power gain (dB) | 
| KP | pentode for output stage | 
| KPP | dual pentode for output stage | 
| KT | triode for output stage | 
| KTt | tetrode for output stage | 
| KTT | dual triode for output stage | 
| L | inductivity | 
| m | external shield (metallizing) | 
| max | maximal value (on currents and voltages it is limit root-mean-square value) | 
| mg | magnetic (deflection, focusing) | 
| mikro | microfonic amplification | 
| min | minimum value; minute | 
| mod | modulator; modulation | 
| mod % | depth of modulation | 
| mod/a | anode modulation | 
| mod/ai | anode pulse modulation | 
| mod/a+g2 | common modulation on anode and second grid | 
| mod/g | grid modulation | 
| mod/g1 | modulation on first grid | 
| mod/g2 | modulation on second grid | 
| mod/g3 | modulation on third grid | 
| mod/ip | pulse modulation | 
| mp | mechanical strength | 
| mA | mili Ampere (10-3 A) | 
| mH | mili Henry (10-3 H) | 
| mV | mili Volt (10-3 V) | 
| mW | mili Watt (10-3 W) | 
| M | photocell sensitive to blue light (category 14) | 
| M | cathode-ray tube with blue luminescent screen (category 13) | 
| Mc/s | megacycle per second (106 c/s, mega Hertz) | 
| MB | cathode-ray tube with blue-white luminescent screen (category 13) | 
| MΩ | mega Ω (106 Ω) | 
| nH | nano Henry (10-9 H) | 
| N | number determining dividing voltage in stabiliser | 
| NE | electron multiplier tube | 
| osc | oscillator, intended as oscillator (adjective) | 
| ov | tap in filament | 
| O | cathode-ray tube with orange luminescent screen (category 13) | 
| P | cathode-ray tube with long afterglow (category 13) | 
| pento | pentode connection | 
| pg | space charge grid | 
| pp | gas-filled tube (or mercury vapour) | 
| pF | pico Farad (10-12 F) | 
| Po | anode dissipation | 
| Po max | limit anode dissipation | 
| Pa | anode power input | 
| Pa max | limit anode power input | 
| Pb | driving power | 
| Pg0 max | limit dissipation in control grid | 
| Pg2 | dissipation in screen grid | 
| Pn | surge power | 
| P šd/PšR | noise temperature (ratio of noise power of diode to noise power of resistance) | 
| Pv | output power | 
| PP | push-pull connection | 
| r | cathode-ray tube with short afterglow (category 13) | 
| R | active resistance | 
| Ra | anode working (matching) external resistance | 
| Raa | working (matching) resistance from anode to anode (in push pull connection) | 
| Rad | anode filtration resistor | 
| Ra min | minimum anode resistance | 
| Rb | base resistance | 
| Rb1 | resistance of base 1 | 
| Rb2 | resistance of base 2 | 
| Rb1b2 | resistance between bases 1 and 2 | 
| Rc | collector resistance | 
| Rem | emitter resistance | 
| Rf | resistance of filament (or heating wire) | 
| Rfk | resistance between filament and cathode | 
| Rg1 | bleeder resistor on first grid | 
| Rg1 max | limit bleeder resistor on first grid | 
| Rg2 | serial resistor on second grid | 
| Rg1g3 | common bleeder resistor od first and third grid | 
| Rg2g4 | common serial resistor od second and fourth grid | 
| Rg3 | bleeder resistor on third grid | 
| Rgo | grid resistor in oscillator | 
| Ri | internal resistance | 
| Ri max | maximal internal resistance | 
| Rk | cathode resistor | 
| Rp | parallel resistance | 
| Rš ekv | equivalent noise resistance | 
| Rtč | resistance of thermoelectric cell | 
| Rt min | minimum necessary resistance of winding in transformer | 
| Rv | input resistance (category 16, 17) | 
| Rvs | output resistance (category 16, 17) | 
| Rz | reverse resistance | 
| s | cathode-ray tube with middle afterglow (category 13) | 
| sem | secondary emission | 
| sig | signal; intended to working with signal (adjective) | 
| sig max | maximum signal | 
| sig min | minimum signal | 
| sk | glass | 
| sv | vertical deflection | 
| S | mutual conductance | 
| Sd1d2 | sensitivity of deflecting plates 1 and 2 | 
| Sd3d4 | sensitivity of deflecting plates 3 and 4 | 
| Sef | effective mutual conductance | 
| Sg3 | mutual conductance, when voltage of third grid varies | 
| Si | silicon (silicium) | 
| Sp | variable mutual conductance | 
| Ss | conversion transconductance | 
| tetro | tetrode connection | 
| ti | pulse width (duration) | 
| tp | hardened resin | 
| trio | triode connection | 
| tžh | warm-up time [min] | 
| T | triode | 
| Tt | tetrode | 
| Tv | television,  intended to television (adjective) | 
| Ua | anode voltage | 
| Ua1 | voltage of first anode | 
| Ua2 | voltage of second anode | 
| Ua3 | voltage of third anode | 
| Ua ef | output voltage (root-mean-square value) | 
| Ua ip vh | peak anode voltage in pulse operation | 
| Ua max | maximum anode voltage | 
| Ua vh | limit peak anode voltage (on diode) | 
| Uaz vh | limit peak reverse anode voltage | 
| Ub | supply voltage | 
| Ub max | maximum supply voltage | 
| Uc | collector voltage | 
| Ud | diode voltage (in combined tubes only) | 
| Ud1 | voltage on first diode (in combined tubes only) | 
| Ud2 | voltage on second diode (in combined tubes only) | 
| Ud3 | voltage on third diode (in combined tubes only) | 
| Ud vh | limit peak voltage on diode (in combined tubes) | 
| Ue | voltage between first and aftermost electrode in stabilizer | 
| Uem | emitter voltage | 
| Uf | filament voltage | 
| Ufk max | limit voltage between filament and cathode | 
| - Ug1 | negative bias voltage on first grid | 
| Ug2 | voltage of second grid | 
| Ug2 max | maximum voltage of second grid | 
| Ug3 | voltage of third grid | 
| Ug3 max | maximum voltage of third grid | 
| Ug4 | voltage of fourth grid | 
| Ug4g6 | voltage of fourth and sixth grid | 
| Ug5 | voltage of fifth grid | 
| Ug ef | voltage of first grid (root-mean-square value) | 
| Ugg | voltage between grids in push-pull connection | 
| Ugg ef | voltage between grids in push-pull connection (root-mean-square value) | 
| Ug max | maximum voltage of grid | 
| Ugp | limit of variable grid bias voltage | 
| Ug vh | limit peak voltage of first grid | 
| Uk | cathode voltage | 
| Ukz | voltage of secondary emission | 
| Umax | limit voltage | 
| Uo | oscillator voltage | 
| Uo ef | root-mean-square value of oscillator voltage | 
| Uo vh | peak oscillator voltage | 
| Up | operation voltage | 
| Ust | voltage of screen | 
| Ut | voltage of cell | 
| Uv | tube voltage drop | 
| Uz | reverse voltage | 
| Uzap | ignition voltage | 
| vaku | vacuum (adjective) | 
| vh | limit peak value | 
| vo | wax | 
| vod | water cooling | 
| vs | internal screening | 
| vv | horizontal deflection | 
| vvf | very high frequency | 
| V | Volt (unit of electric voltage) | 
| Vys | tube is using also as transmitting tube | 
| W | Watt (unit of electric power) | 
| zes | amplifier | 
| zes ip | pulse amplifier | 
| zes mf | intermediate-frequency amplifier | 
| zes nf | audio amplifier | 
| zes vf | high-frequency amplifier | 
| zesv | power amplifier | 
| zesv nf | audio power amplifier | 
| zesv vf | high-frequency power amplifier | 
| zes A | amplifier in class A | 
| zes AB | amplifier in class AB | 
| zes B | amplifier in class B | 
| zes C | amplifier in class C | 
| zes O | video amplifier | 
| zp | parallel connection | 
| zs | connection in series | 
| zzg | common grid circuit | 
| zzk | common cathode circuit | 
| Z | photocell sensitive to green light (category 14) | 
| Z | cathode-ray tube with green luminescent screen (category 13) | 
| Zmf | intermediate-frequency impedance | 
| ZM | cathode-ray tube with green-blue luminescent screen (category 13) | 
| ZŽ | cathode-ray tube with green-yellow luminescent screen (category 13) | 
| Ž | cathode-ray tube with yellow luminescent screen (category 13) | 
| α | angle of screen | 
| γ | sensitivity | 
| γ s | deflection sensitivity of plates near the screen in CRT | 
| θ | temperature | 
| θ o | ambient tempetarure | 
| θ max | maximum operating temperatutre | 
| θ min | minimum operating temperatutre | 
| λ min | minimum wawelength | 
| μ | multiplication factor | 
| μA | mikro Ampere (10-6 A) | 
| μF | mikro Farad (10-6 F) | 
| μH | mikro Henry (10-6 H) | 
| μV | mikro Volt (10-6 V) | 
| σ | ratio between open-circuit voltage on secondary winding to current in primary winding on maximum primary load (approximative value) | 
| Ω | ohm (unity of electric resistance) |