- behaving in a theatrical, lively, or ingratiating way: Around close friends, one doesn't have to be on every minute.
- functioning or performing at one's best: When she's on, no other tennis player is half as good.
- on a dime,
- on a first-name basis,
- on a limb,
- on a par with,
- on a pedestal, put
Origin of on
- regularly taking (a drug)she's on the pill
- addicted tohe's on heroin
- staked or wagered as a betten pounds on that horse
- charged tothe drinks are on me
adverb (often used as a particle)
- performing, as on stageI'm on in five minutes
- definitely taking placethe match is on for Friday; their marriage is still on
- tolerable, practicable, acceptable, etcyour plan just isn't on
- (of a person) willing to do something
- (modifier) relating to or denoting the leg side of a cricket field or pitchthe on side; an on drive
- (in combination) used to designate certain fielding positions on the leg sidelong-on; mid-on
Word Origin for on
Old English on, unstressed variant of an "in, on, into," from Proto-Germanic *ana "on" (cf. Dutch aan, German an, Gothic ana "on, upon"), from PIE root *an- "on" (cf. Avestan ana "on," Greek ana "on, upon," Latin an-, Old Church Slavonic na, Lithuanian nuo "down from"). Also used in Old English in many places where we would now use in. From 16c.-18c. (and still in northern England dialect) often reduced to o'. Phrase on to "aware" is from 1877. On time is from 1890.
see be on to.