<; 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.
abbr.
- initiation factor
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