Merriam-Webster Collegiate Dictionary - on

 or Ont  abbreviation Ontario ON  I. prepositi~  Etymology: Middle English an, ~, prepositi~ & adverb, from Old English; akin to Old High German ana ~, Greek ana up, ~  Date: before 12th century  1.  a. — used as a functi~ word to indicate positi~ in c~tact with and supported by the top surface of the book is lying ~ the table  b. — used as a functi~ word to indicate positi~ in or in c~tact with an outer surface the fly landed ~ the ceiling I have a cut ~ my finger paint ~ the wall  c. — used as a functi~ word to indicate positi~ in close proximity with a village ~ the sea stay ~ your opp~ent  d. — used as a functi~ word to indicate the locati~ of something ~ the left ~ the south side of the house ~ the farm  2.  a. — used as a functi~ word to indicate a source of attachment or support ~ a string stand ~ ~e foot hang it ~ a nail  b. — used as a functi~ word to indicate a source of dependence you can rely ~ me feeds ~ insects lives ~ a pensi~  c. — used as a functi~ word to indicate means of c~veyance ~ the bus  d. — used as a functi~ word to indicate presence in the possessi~ of had a knife ~ him  3. — used as a functi~ word to indicate a time frame during which something takes place a parade ~ Sunday or an instant, acti~, or occurrence when something begins or is d~e ~ cue ~ arriving home, I found your letter news ~ the hour cash ~ delivery  4. archaic of  5.  a. — used as a functi~ word to indicate manner of doing something; often used with the ~ the sly keep everything ~ the up-and-up  b. — used as a functi~ word to indicate means or agency cut myself ~ a knife talk ~ the teleph~e  c. — used as a functi~ word to indicate a medium of expressi~ ~ stage best show ~ televisi~  6.  a.  (1) — used as a functi~ word to indicate active involvement in a c~diti~ or status ~ the increase ~ the lookout  (2) regularly using or showing the effects of using ~ drugs  b. — used as a functi~ word to indicate involvement or participati~ ~ tour ~ the team ~ duty  c. — used as a functi~ word to indicate inclusi~ put it ~ the agenda  d. — used as a functi~ word to indicate positi~ or status in proper relati~ship with a standard or objective ~ schedule  7.  a. — used as a functi~ word to indicate reas~, ground, or basis (as for an acti~, opini~, or computati~) I have it ~ good authority ~ ~e c~diti~ the interest will be 10 cents ~ the dollar  b. — used as a functi~ word to indicate the cause or source profited ~ the sale of stock  c. — used as a functi~ word to indicate the focus of obligati~ or resp~sibility drinks are ~ the house put the blame ~ me  8.  a. — used as a functi~ word to indicate the object of collisi~, oppositi~, or hostile acti~ bumped my head ~ a limb an attack ~ religi~ pulled a gun ~ me  b. — used as a functi~ word to indicate the object with respect to some disadvantage, handicap, or detriment has three inches in height ~ me a 3-game lead ~ the sec~d-place team the joke's ~ me  9.  a. — used as a functi~ word to indicate destinati~ or the focus of some acti~, movement, or directed effort crept up ~ him feast your eyes ~ this working ~ my skiing made a payment ~ the loan  b. — used as a functi~ word to indicate the focus of feelings, determinati~, or will have pity ~ me keen ~ sports a curse ~ you  c. — used as a functi~ word to indicate the object with respect to some misfortune or disadvantageous event the crops died ~ them  d. — used as a functi~ word to indicate the subject of study, discussi~, or c~siderati~ a book ~ insects reflect ~ that a moment agree ~ price  e. with respect to go light ~ the salt short ~ cash  10. — used as a functi~ word to indicate reduplicati~ or successi~ in a series loss ~ loss  II. adverb  Date: before 12th century  1.  a. in or into a positi~ of c~tact with an upper surface especially so as to be positi~ed for use or operati~ put the plates ~  b. in or into a positi~ of being attached to or covering a surface; especially in or into the c~diti~ of being worn put his new shoes ~  2.  a. forward or at a more advanced point in space or time went ~ home later ~  b. in c~tinuance or successi~ rambled ~ and so ~  3. into operati~ or a positi~ permitting operati~ switched the light ~  III. adjective  Date: circa 1541  1. engaged in an activity or functi~ (as a dramatic role)  2.  a.  (1) being in operati~ the radio is ~  (2) placed so as to permit operati~ the switch is ~  b. taking place or being broadcast the game is ~  3. aware of something — usually used with to my boss was ~ to me  4. intended, planned has nothing ~ for t~ight  5. British talking or harping incessantly — used with about  6. chiefly British regarded as possible or feasible — usually used in negative c~structi~s  7.  a. engaged in or as if in a performance the comedian was always ~  b. being at a high level of performance ON  I. noun suffix  Etymology: International Scientific Vocabulary, alteration of ~e chemical compound not a ketone or other oxo compound parathion  II. noun suffix  Etymology: from ~ (in ion)  1. subatomic particle nucleon  2.  a. unit ; quantum photon magneton  b. basic hereditary component cistron operon  III. noun suffix  Etymology: New Latin, from ~ (in argon) noble gas radon