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1. Neutral chemical compound, especially:
a. Neutral carbohydrate: inulin.
b. Protein or protein derivative: albumin.
c. Lipid or lipid derivative: lecithin.
d. Enzyme: pancreatin.
e. Glycoside: chitin.
2. A pharmaceutical: rifampin.
3. An antibiotic: penicillin.
4. Antigen: tuberculin.
5. Variant of -ine2..

[Variant of -ine.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


suffix forming nouns
1. indicating a neutral organic compound, including proteins, glucosides, and glycerides: insulin; digitoxin; tripalmitin.
2. indicating an enzyme in certain nonsystematic names: pepsin.
3. (Pharmacology) indicating a pharmaceutical substance: penicillin; riboflavin; aspirin.
4. indicating a chemical substance in certain nonsystematic names: coumarin.
[from New Latin -ina; compare -ine2]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


1. (used to indicate inclusion within space, a place, or limits): walking in the park.
2. (used to indicate inclusion within something abstract or immaterial): in politics; in the autumn.
3. (used to indicate inclusion within or occurrence during a period or limit of time): in ancient times; a task done in ten minutes.
4. (used to indicate limitation or qualification, as of situation, condition, relation, manner, action, etc.): to speak in a whisper.
5. (used to indicate means): spoken in French.
6. (used to indicate motion or direction from outside to a point within) into: Let's go in the house.
7. (used to indicate transition from one state to another): to break in half.
8. (used to indicate object or purpose): speaking in honor of the event.
9. in or into some place, position, state, relation, etc.: Please come in.
10. on the inside; within.
11. in one's house or office.
12. in office or power.
13. in possession or occupancy.
14. having the turn to play, as in a game.
15. Baseball. (of an infielder or outfielder) in a position closer to home plate than usual; short: The third baseman played in.
16. on good terms; in favor: in with his boss.
17. in vogue; in style: Hats are in this year.
18. in season.
19. inner; internal: the in part of a mechanism.
a. in favor with advanced or sophisticated people; fashionable; stylish: the in place to dine.
b. comprehensible only to a special group: an in joke.
21. included in a favored group.
22. inbound: an in train.
23. plentiful; available.
24. being in power: the in party.
25. Usu., ins. persons who are in.
26. pull or influence: He's got an in with the senator.
27. a valid or playable return or service in sports.
1. in for, certain to undergo (a disagreeable experience).
2. in for it, Slang. about to suffer punishment or unpleasant consequences.
3. in like Flynn, Slang. in circumstances of assured success.
4. in that, because; inasmuch as.
[before 900; Middle English, Old English, c. Old Frisian, Old Saxon, Old High German]




Chem. Symbol.


a prefix representing English in (income; indwelling; inland), used also as a verb-formative with transitive, intensive, or sometimes little apparent force (intrust; ingulf). It often assumes the same forms as in- 2, such as en-1, em-1, im-3.
[Middle English, Old English; see in]


a prefix of Latin origin meaning primarily “in,” but used also as a verb-formative with the same force as in-1 (incarcerate; incantation).
Also, il- , im-, ir-. Compare em- 1 , en-1.


a prefix of Latin origin, corresponding to English un-, having a negative or privative force, freely used as an English formative, esp. of adjectives and their derivatives and of nouns (indefensible; inexpensive; invariable). It has the same variants before consonants as in-2 (immeasurable; illiterate; irregular, etc.). Compare il- 2 , im-2, ir-2.


a noun suffix used in chemical nomenclature (glycerin; acetin). In spelling, usage wavers between -in and -ine. In chemistry a certain distinction of use is attempted, basic substances having the termination -ine rather than -in (ammine; aniline), and -in being restricted to certain neutral compounds, glycerides, glucosides, and proteids (albumin), but this distinction is not always observed.
[< New Latin -ina. See -ine2]


a suffixal use of the adverb in, extracted from sit-in, forming nouns, usu. from verbs, referring to organized protests through or in support of the named activity (kneel-in; pray-in) or, more generally, to any organized social or cultural activity (cook-in; sing-in).


Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.