εἰ

ei. a primary particle of conditionality; if, whether, that, etc.:--forasmuch as, if, that, (al-)though, whether. Often used in connection or composition with other particles, especially as in εἴγε, εἰ δὲ μή(γε), εἰ καί, εἰ μή, εἰ μή τι, εἴ περ, εἴ πως, εἴ τις, ἐκ. See also ἐάν.