If

Conditional marker

It is conventional in grammar to speak of the words which follow if (French si) as a condition for the truth of the main clause statement.

• If we don't finish tonight, we'll finish in the morning.
• I only sweep that room if I have time.

(In the second case, if is equivalent to when and similar to as long as (tant que).

In the study of language, the if-clause is called the protase (cf. French explanation)</span> of a conditional.

Logic

If is an important logical operator. In a sentence like: If A, then B.

• If A is true, B is true.
• If A is false, B can be true or false.

Synonyms

• provided that
• providing that
• on the condition that
• as long as

Derived words

iffy (adj.) - uncertain