olemus
ISO/IEC 2382:
eeldefineeritud identifikaator, mida programmeerija ei saa ümber defineerida
= predefined identifier that cannot be redefined by a programmer

ISO/IEC/IEEE 24765:
programmikeele sõna, mille tähendus on määratud selle keele reeglitega ja mida mingis või mitte üheski kontekstis ei saa programmeerija kasutada muuks otstarbeks; näiteks IF, THEN, WHILE
= word in a programming language, of which the meaning is fixed by the rules of that language and which, in certain or all contexts, cannot be used by the programmer for any purpose other than its intended one
EXAMPLE: IF, THEN, WHILE

Wiktionary:
(programming) a string of characters that is a verb, command or other part of a programming language, and therefore cannot be used as the name of a variable, constant, function or procedure

ülevaateid
https://en.wikipedia.org/wiki/Reserved_word