Etymology: Middle English an, on, preposition & adverb, from Old English; akin to Old High German ana on, Greek ana up, on
Date: before 12th century
1 a —used as a function word to indicate position in contact with and supported by the top surface of <the book is lying on the table>b —used as a function word to indicate position in or in contact with an outer surface <the fly landed on the ceiling><I have a cut on my finger><paint on the wall>c —used as a function word to indicate position in close proximity with <a village on the sea><stay on your opponent>d —used as a function word to indicate the location of something <on the left><on the south side of the house><on the farm> 2 a —used as a function word to indicate a source of attachment or support <on a string><stand on one foot><hang it on a nail>b —used as a function word to indicate a source of dependence <you can rely on me><feeds on insects><lives on a pension>c —used as a function word to indicate means of conveyance <on the bus>d —used as a function word to indicate presence in the possession of <had a knife on him> 3 —used as a function word to indicate a time frame during which something takes place <a parade on Sunday> or an instant, action, or occurrence when something begins or is done <on cue><on arriving home, I found your letter><news on the hour><cash on delivery> 4archaic:of 5 a —used as a function word to indicate manner of doing something ; often used with the<on the sly><keep everything on the up-and-up>b —used as a function word to indicate means or agency <cut myself on a knife><talk on the telephone>c —used as a function word to indicate a medium of expression <on stage><best show on television> 6 a (1) —used as a function word to indicate active involvement in a condition or status <on the increase><on the lookout>(2): regularly using or showing the effects of using <on drugs>b —used as a function word to indicate involvement or participation <on tour><on the team><on duty>c —used as a function word to indicate inclusion <put it on the agenda>d —used as a function word to indicate position or status in proper relationship with a standard or objective <on schedule> 7 a —used as a function word to indicate reason, ground, or basis (as for an action, opinion, or computation) <I have it on good authority><on one condition><the interest will be 10 cents on the dollar>b —used as a function word to indicate the cause or source <profited on the sale of stock>c —used as a function word to indicate the focus of obligation or responsibility <drinks are on the house><put the blame on me> 8 a —used as a function word to indicate the object of collision, opposition, or hostile action <bumped my head on a limb><an attack on religion><pulled a gun on me>b —used as a function word to indicate the object with respect to some disadvantage, handicap, or detriment <has three inches in height on me><a 3-game lead on the second-place team><the joke's on me> 9 a —used as a function word to indicate destination or the focus of some action, movement, or directed effort <crept up on him><feast your eyes on this><working on my skiing><made a payment on the loan>b —used as a function word to indicate the focus of feelings, determination, or will <have pity on me><keen on sports><a curse on you>c —used as a function word to indicate the object with respect to some misfortune or disadvantageous event <the crops died on them>d —used as a function word to indicate the subject of study, discussion, or consideration <a book on insects><reflect on that a moment><agree on price>e: with respect to <go light on the salt><short on cash> 10 —used as a function word to indicate reduplication or succession in a series <loss on loss>