What does idle mean?
Idle describes a person, machine, activity, or period that is inactive, unoccupied, or unproductive. A person may be called idle for doing nothing, while an idle engine is running without performing work. Idle machines or systems are also often described as unused or temporarily inactive. As a verb, idle means to remain without meaningful activity, usually deliberately: someone can idle in a café, idle around a town, or allow an engine to idle. The adjective is sometimes neutral and sometimes disapproving, depending on context; describing a person as idle commonly implies that they could be doing something useful. In technical language, an engine's idle is its low-speed running condition, maintained when the engine is on but not engaged in productive work. The word is common in both British and American English and appears in familiar combinations such as go idle, sit idle, idle time, and let the engine idle.
Not working, active, or occupied; inactive, unused, or producing no effect.
"The machine has been idle since the production line was shut down."
The term is neutral in many technical contexts but can imply fault or waste when applied to a person or period.
To spend time doing nothing or without meaningful activity.
"They idled outside the station until the train arrived."
Often implies a deliberate or prolonged period of inactivity, though it can also describe temporary inactivity.
A state of inactivity, especially the neutral running state of an engine or other mechanism.
"The driver allowed the engine to return to idle."
This noun use is mainly technical; the plural is uncommon.
Rare. The noun is more often used in the singular or without a plural, as in “the engine is at idle.”
"The control panel provides idles for both the main engine and the auxiliary engine."
Idle descends from Latin otium, meaning leisure: the same root that gave us otiose and negotiate.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of idle
Idle entered Middle English as idel, borrowed from Old French idel, which came from Latin otiosus, meaning “at leisure” or “unoccupied.” Latin otiosus was derived from otium, the Latin word for leisure or inactivity. The Latin root otium also underlies English words such as otiose and negotiate, the latter through the Latin intensive form negotium.
Related word forms
How idle is actually used
As an adjective, idle can be neutral, especially in technical contexts, but it often carries a mildly critical implication of wasted time or inactivity. The verb similarly suggests deliberately doing nothing for an extended period. In descriptions of engines and machinery, idle refers specifically to a neutral running state.
Easily confused with idle
Idle means inactive or unoccupied, whereas ideal means the best possible or a perfect model.