If

Part of speech: conjunction, noun

Definitions

1. Introduces a condition on which another outcome depends ; expresses uncertainty about whether something is the case ; a stipulation or doubtful supposition that something may or may not happen
2. Sets a condition under which something will occur ; introduces an indirect question about whether a fact holds ; a condition, reservation, or uncertain possibility attached to an outcome
3. Marks a requirement that a result hinges on ; links a clause expressing doubt about whether something is true ; a noun for an unresolved condition or qualification placed on a plan

Etymology: The small word "if" is older than most of English's grammar words, and its ancestor was once a different kind of word altogether. Its Old English form, "ġif," came from a Proto-Germanic root "*jabai," meaning "when" or "if," and that root has cousins across the North Sea family of languages: Dutch "of," German "ob," West Frisian "oft," and Icelandic "ef" all still carry the same sense of "whether" or "if." The English word was once "gif" and "yif" in Middle English spellings, and the modern form simply wore down over time. The surprise is how close "if" sits to words that now look unrelated. Dutch "of" means "or," and German "ob" means "whether," so the same ancestor produced both a conditional and a choice between options. In English the two meanings split apart, leaving "if" to express conditions and "whether" to take over the sense of choosing between alternatives.

Synonyms: provided, assuming