If

[if] /ɪf/

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.
noun
6.
a supposition; uncertain possibility:
The future is full of ifs.
7.
a condition, requirement, or stipulation:
There are too many ifs in his agreement.
Idioms
8.
ifs, ands, or buts, reservations, restrictions, or excuses:
I want that job finished today, and no ifs, ands, or buts.
Radio.
1.
.
/ɪf/
conjunction (subordinating)
1.
in case that, or on condition that: if 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 though: an attractive if awkward girl
4.

5.
as if, as it would be if; as though: he treats me as if I were junior to him
noun
6.
an uncertainty or doubt: the big if is whether our plan will work at all
7.
a condition or stipulation: I won’t have any ifs or buts
abbreviation
1.
intermediate frequency
noun

See interactive fiction
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.

IF abbr.
initiation factor
1.
infertility
2.
interferon
3.
intermediate frequency