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if

[if]
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conjunction
  1. in case that; granting or supposing that; on condition that: Sing if you want to. Stay indoors if it rains. I'll go if you do.
  2. even though: an enthusiastic if small audience.
  3. whether: He asked if I knew Spanish.
  4. (used to introduce an exclamatory phrase): If only Dad could see me now!
  5. when or whenever: If it was raining, we had to play inside.
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noun
  1. a supposition; uncertain possibility: The future is full of ifs.
  2. a condition, requirement, or stipulation: There are too many ifs in his agreement.
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Idioms
  1. ifs, ands, or buts, reservations, restrictions, or excuses: I want that job finished today, and no ifs, ands, or buts.
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Origin of if

before 900; Middle English, variant of yif, Old English gif, gef; akin to Old Norse ef if, Gothic ibai whether, Old High German iba condition, stipulation

Synonyms

See more synonyms for if on Thesaurus.com
1, 2. If, provided, providing imply a condition on which something depends. If is general. It may be used to indicate suppositions or hypothetical conditions (often involving doubt or uncertainty): If you like, we can go straight home. If I had known, I wouldn't have gone. If may mean even though: If I am wrong, you are not right. It may mean whenever: If I do not understand, I ask questions. Provided always indicates some stipulation: I will subscribe ten dollars provided ( on the condition ) that you do, too. Provided he goes, we can go along. Providing means the same as provided, that is, just in case some certain thing should happen: We will buy the house, providing ( provided ) we can get a mortgage.

Usage note

If meaning “whether,” as in I haven't decided if I'll go, is sometimes criticized, but the usage has been established in standard English for a long time.

if

or IF

Radio.
  1. intermediate frequency.
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Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for if

if

conjunction (subordinating)
  1. in case that, or on condition thatif you try hard it might work; if he were poor, would you marry him?
  2. used to introduce an indirect question. In this sense, if approaches the meaning of whether
  3. even thoughan attractive if awkward girl
    1. used to introduce expressions of desire, with onlyif I had only known
    2. used to introduce exclamations of surprise, dismay, etcif this doesn't top everything!
  4. as if as it would be if; as thoughhe treats me as if I were junior to him
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noun
  1. an uncertainty or doubtthe big if is whether our plan will work at all
  2. a condition or stipulationI won't have any ifs or buts
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Word Origin

Old English gif; related to Old Saxon ef if, Old High German iba whether, if

IF

i.f.

abbreviation for
  1. intermediate frequency
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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for if

conj.

Old English gif (initial g- in Old English pronounced with a sound close to Modern English -y-), from Proto-Germanic *ja-ba (cf. Old Saxon, Old Norse ef, Old Frisian gef, Old High German ibu, German ob, Dutch of "if, whether"), from PIE pronomial stem *i- [Watkins]; Klein, OED suggest probably originally from an oblique case of a noun meaning "doubt" (cf. Old High German iba "condition, stipulation, doubt," Old Norse if "doubt, hesitation," Swedish jäf "exception, challenge"). As a noun from 1510s.

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Online Etymology Dictionary, © 2010 Douglas Harper

if in Medicine

IF

abbr.
  1. initiation factor
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The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Idioms and Phrases with if

if

In addition to the idioms beginning with if

  • if anything
  • if at first you don't succeed, try, try again
  • if it ain't broke don't fix it
  • if only
  • if the mountain won't come to Muhammad, Muhammad must go to the mountain
  • if the shoe fits, wear it
  • if wishes were horses
  • if worst comes to worst
  • if you can't beat 'em, join 'em
  • if you can't stand the heat, get out of the kitchen

also see:

  • as if
  • damned if I do, damned if I don't
  • make as if to
  • no ifs or buts
  • nothing if not
  • (if) push comes to shove
  • what if
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The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.