if

conj. [ OE. if, gif, AS. gif; akin to OFries. ief, gef, ef, OS. ef, of, D. of, or, whether, if, G. ob whether, if, OHG. oba, ibu, Icel. ef, Goth. iba, ibai, an interrogative particle; properly a case form of a noun meaning, doubt (cf. OHG. iba doubt, condition, Icel. if, ef, ifi, efi), and therefore orig. meaning, on condition that. ] 1. In case that; granting, allowing, or supposing that; -- introducing a condition or supposition. [ 1913 Webster ]

Tisiphone, that oft hast heard my prayer,
Assist, if Œdipus deserve thy care. Pope. [ 1913 Webster ]

If thou be the Son of God, command that these stones be made bread. Matt. iv. 3. [ 1913 Webster ]

2. Whether; -- in dependent questions. [ 1913 Webster ]

Uncertain if by augury or chance. Dryden. [ 1913 Webster ]

She doubts if two and two make four. Prior. [ 1913 Webster ]

As if,
But if. See under As, But. [ 1913 Webster ]