(used to indicate inclusion within space, a place, or limits): walking in the park.
(used to indicate inclusion within something abstract or immaterial): in politics; in the autumn.
(used to indicate inclusion within or occurrence during a period or limit of time): in ancient times; a task done in ten minutes.
(used to indicate limitation or qualification, as of situation, condition, relation, manner, action, etc.): to speak in a whisper; to be similar in appearance.
(used to indicate means): sketched in ink; spoken in French.
(used to indicate motion or direction from outside to a point within) into: Let's go in the house.
(used to indicate transition from one state to another): to break in half.
(used to indicate object or purpose): speaking in honor of the event.
in or into some place, position, state, relation, etc.: Please come in.
on the inside; within.
in one's house or office.
in office or power.
in possession or occupancy.
having the turn to play, as in a game.
Baseball. (of an infielder or outfielder) in a position closer to home plate than usual; short: The third baseman played in, expecting a bunt.
on good terms; in favor: He's in with his boss, but he doubts it will last.
in vogue; in style: He says straw hats will be in this year.
in season: Watermelons will soon be in.
located or situated within; inner; internal: the in part of a mechanism.
in favor with advanced or sophisticated people; fashionable; stylish: the in place to dine; Her new novel is the in book to read this summer.
comprehensible only to a special or ultrasophisticated group: an in joke.
well-liked; included in a favored group.
inward; incoming; inbound: an in train.
plentiful; available.
being in power, authority, control, etc.: a member of the in party.
playing the last nine holes of an eighteen-hole golf course (opposed to out ): His in score on the second round was 34.
Usually, ins. persons in office or political power (distinguished from outs ).
a member of the political party in power: The election made him an in.
pull or influence; a social advantage or connection: He's got an in with the senator.
(in tennis, squash, handball, etc.) a return or service that lands within the in-bounds limits of a court or section of a court (opposed to out ).
verb (used with object), inned, inning. British Dialect.
to enclose.
be in for, to be bound to undergo something, especially a disagreeable experience: We are in for a long speech.
in for it, Slang. about to suffer chastisement or unpleasant consequences, especially of one's own actions or omissions: I forgot our anniversary again, and I'll be in for it now. Also, British, for it.
in that, because; inasmuch as: In that you won't have time for supper, let me give you something now.
in with, on friendly terms with; familiar or associating with: They are in with all the important people.

before 900; 1925–30 for def 28; Middle English, Old English; cognate with German, Dutch, Old Frisian, Old Saxon, Gothic in, Old Norse ī, Latin in, Greek en, Lithuanian į Unabridged


Indiana (approved especially for use with zip code).


Symbol, Chemistry.


a prefix representing English in (income; indwelling; inland , etc.), but used also as a verb-formative with transitive, intensive, or sometimes little apparent force (intrust; inweave , etc.). It often assumes the same forms as in-2, such as en-, em-, 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-, en-.

< Latin, combining form of in (preposition); cognate with in


a prefix of Latin origin, corresponding to English un-, having a negative or privative force, freely used as an English formative, especially of adjectives and their derivatives and of nouns (inattention; indefensible; inexpensive; inorganic; invariable ). It assumes the same phonetic phases as in-2. (impartial; immeasurable; illiterate; irregular , etc.). In French, it became en- and thus occurs unfelt in such words as enemy (French ennemi, Latin inimicus, lit., not friendly).
Also, il-, im-, ir-.

< Latin; akin to an-1, a-6, un-1

The prefixes in- and un- may both have, among other uses, a negative force. In- is the form derived from Latin, and is therefore used in learned words or in words derived from Latin or (rarely) Greek: inaccessible, inaccuracy, inadequate, etc. Un- is the native form going back to Old English, used in words of native origin, and sometimes used in combination with words of other origins if these words are in common use: unloving, ungodly, unfeeling, unnecessary, unsafe.


a suffix, occurring in adjectives of Greek and Latin origin, meaning “pertaining to,” and (in nouns thence derived) also imitated in English (coffin; cousin , etc.).

Middle English -in, -ine < Old French < Latin -inus, -ina, -inum < Greek -inos, -inē, -inon


a noun suffix used in a special manner in chemical and mineralogical nomenclature (glycerin; acetin , etc.). 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 (aconitine; aniline , etc.), and -in being restricted to certain neutral compounds, glycerides, glucosides, and proteids (albumin; palmitin , etc.), but this distinction is not always observed.

< Neo-Latin -ina. See -ine2


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


inch; inches. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
Cite This Source Link To in
World English Dictionary
in1 (ɪn)
1.  inside; within: no smoking in the auditorium
2.  at a place where there is: lying in the shade; walking in the rain
3.  indicating a state, situation, or condition: in a deep sleep; standing in silence
4.  before or when (a period of time) has elapsed: come back in one year
5.  using (a language, etc) as a means of communication: written in code
6.  concerned or involved with, esp as an occupation: in journalism
7.  while or by performing the action of; as a consequence of or by means of: in crossing the street he was run over
8.  used to indicate goal or purpose: in honour of the president
9.  (used of certain animals) about to give birth to; pregnant with (specified offspring): in foal; in calf
10.  a variant of into : she fell in the water; he tore the paper in two
11.  ( often foll by an infinitive ) have it in one to have the ability (to do something)
12.  informal (Austral) in it joining in; taking part
13.  (conjunction) in that, in so far as because or to the extent that; inasmuch as: I regret my remark in that it upset you
14.  nothing in it no difference or interval between two things
15.  in or into a particular place; inward or indoors: come in; bring him in
16.  so as to achieve office, power, or authority: the Conservatives got in at the last election
17.  so as to enclose: block in; cover in a hole
18.  (in certain games) so as to take one's turn or one's team's turn at a certain aspect of the play; taking one's innings: you have to get the other side out before you go in
19.  (Brit) (of a fire) alight: do you keep the fire in all night?
20.  (in combination) indicating an activity or gathering, esp one organized to protest against something: teach-in; work-in
21.  in at present at (the beginning, end, etc)
22.  in between between
23.  in for about to be affected by (something, esp something unpleasant): you're in for a shock
24.  in on acquainted with or sharing in: I was in on all his plans
25.  in with associated with; friendly with; regarded highly by
26.  informal have it in for, have got it in for to wish or intend harm towards
27.  (stressed) fashionable; modish: the in thing to do
28.  (NZ) competing: you've got to be in to win
29.  ins and outs intricacies or complications; details: the ins and outs of a computer system
[Old English; compare Old High German in, Welsh yn, Old Norse ī, Latin in, Greek en]

the internet domain name for

the chemical symbol for

abbreviation for

abbreviation for

in-, il-, im- or ir-1
Compare un- not; non-: incredible; insincere; illegal; imperfect; irregular
[from Latin in-; related to ne-, nōn not]
il-, il-, im- or ir-1
[from Latin in-; related to ne-, nōn not]
im-, il-, im- or ir-1
[from Latin in-; related to ne-, nōn not]
ir-, il-, im- or ir-1
[from Latin in-; related to ne-, nōn not]

in-, il-, im- or ir-2
1.  in; into; towards; within; on: infiltrate; immigrate
2.  having an intensive or causative function: inflame; imperil
[from in (prep, adv)]
il-, il-, im- or ir-2
[from in (prep, adv)]
im-, il-, im- or ir-2
[from in (prep, adv)]
ir-, il-, im- or ir-2
[from in (prep, adv)]

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.  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 & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009
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Word Origin & History

O.E. in "in," inne "within," from P.Gmc. *in (cf. O.Fris, Du., Ger., Goth. in, O.N. i), from PIE *en-/*n (cf. Gk. en, L. in, O.Ir. in, Welsh yn-, O.C.S. on-). Sense of "holding power" (the in party) first recorded 1605; that of "exclusive" (the in-crowd, an in-joke) is from 1907; that of "stylish, fashionable"
(the in thing) is from 1960. The noun sense of "influence, access" (have an in with) first recorded 1929 in Amer.Eng. In-and-out "copulation" is attested from 1610s.

prefix meaning "not, opposite of, without" (also im-/il-/ir- by assimilation of -n- with following consonant), from L. in- "not," cognate with Gk. an-, O.E. un- (see un- (1)).

prefix meaning "into, in, on, upon" (also im-; il-; ir- by assimilation of -n- with following consonant), from L. in- "in" (see in). In O.Fr. this often became en-, which was usually respelled in Eng. to conform with L., but not always, which accounts for pairs like enquire/inquire.
There was a native form, which in W.Saxon usually appeared as on- (cf. O.E. onliehtan "to enlighten"), and some verbs survived into M.E. (cf. inwrite "to inscribe"), but all now seem to be extinct.

suffix attached to a verb originated 1960 with sit-in (which was probably influenced by sit-down strike), used first of protests, extended c.1965 to any gathering.
Online Etymology Dictionary, © 2010 Douglas Harper
Cite This Source
American Heritage
Medical Dictionary

The symbol for the element indium.

in- 1 or il- or im- or ir-
Not: invertebrate.

in- 2 or il- or im- or ir-
In; into; within: intubation.

-in suff.

  1. Neutral chemical compound: inulin.

  2. Pharmaceutical: rifampin.

  3. Antibiotic: penicillin.

  4. Antigen: tuberculin.

  5. Variant of -ine2.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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American Heritage
Science Dictionary
Abbreviation of inch
The symbol for indium.
indium   (ĭn'dē-əm)  Pronunciation Key 
Symbol In
A soft, malleable, silvery-white metallic element that occurs mainly in ores of zinc and lead. It is used in the manufacture of semiconductors, in bearings for aircraft engines, and as a plating over silver in mirrors. Atomic number 49; atomic weight 114.82; melting point 156.61°C; boiling point 2,080°C; specific gravity 7.31; valence 1, 2, 3. See Periodic Table.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Computing Dictionary

in definition

1. The country code for India.
2. The typical type or "mode" of function parameter that passes information in one direction - from the caller to the function. Other modes are out and inout.

The Free On-line Dictionary of Computing, © Denis Howe 2010
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American Heritage
Abbreviations & Acronyms
The American Heritage® Abbreviations Dictionary, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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American Heritage
Idioms & Phrases


In addition to the idioms beginning with in, also see under out of.

The American Heritage® Dictionary of Idioms by Christine Ammer.
Copyright © 1997. Published by Houghton Mifflin.
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Example sentences for in
Nonetheless, piglet offers the house to owl, and he presumably moves in.
This allows him to know everything about anything in the dimension he is in.
The lift operator brings him to the correct floor, and watches until he went in.
The club has two annual fixtures that it arranges or is involved in.
Idioms & Phrases
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