Other forms: idling, idled, idles
Idle means not working — not running, not being used, not doing anything. A crane standing still over a stopped building site, a factory floor with the lights off, a whole Sunday on the sofa.
The word covers two very different situations, and the difference is blame. Machines and workers are idle when there is nothing for them to do: the diggers stood idle for a week, three hundred staff were left idle by the strike. A person called idle is being accused — the work is there and they are not doing it. Idle also attaches to talk and feelings, where it means with nothing behind it: idle gossip, an idle threat, idle curiosity. As a verb it belongs to engines, which idle when they run gently without moving the car. Keep it apart from idol, which is a statue or a famous person people worship.
1adjectiveidleNot working, not running, not being used.
“The machines sat idle while the parts were on order.”
synonyms: inactive, unused
2adjectivelazyAvoiding work when there is work to be done.
“He called his son idle and went back out to the garden.”
synonyms: lazy
3adjectivewordsSaid of words or feelings with no purpose or substance behind them.
“It was an idle threat and nobody moved.”
4verbengineOf an engine, to run slowly without driving the vehicle forward.
“She left the engine idling at the kerb.”
Also accepted in games: lazy, inactive
Idle goes back through Middle English idel to Old English īdel, and further to Proto-Germanic *īdlaz. Its cousins tell you what the old sense was: Dutch ijdel means vain or meaningless, German eitel means vain and conceited. An idle threat — words with nothing inside them — is that older sense still at work in English.
Proto-Germanic
*īdlaz
Proto-West Germanic
*īdl
Old English
īdel
Middle English
idel
English, today
idle
From Middle English idel, ydel, from Old English īdel, from Proto-West Germanic īdl, from Proto-Germanic īdlaz. Cognate with Dutch ijdel (“vain, meaningless”), ijl (“rareified, skinny”), iel (“thin, slender”); German Low German iedel (“vain, idle”); German eitel (“vain, conceited”); and possibly Old Norse illr "bad"; > English ill.
Etymology from Wiktionary, CC BY-SA