Abarim Publications' online Biblical Greek Dictionary
The particle ει (ei) is a conditional conjunction and means if. It's pretty much on a par with our English word "if", and offers no major surprises. It is employed to introduce a situation or statement that is entirely hypothetical, typically without saying anything about the validity of the statement.
Our particle also serves as element of a few compounds:
- Together with the curious particle αν (an), which expresses supposition or wish: the conjunction εαν (ean), meaning something like "if it would".
- Together with the conjunction τε (te), meaning "and": the conjunction ειτε (eite), meaning "and if" or "whether".
- Together with the nominative single form of the relative pronoun, ος (hos), meaning "that/who/which": the adverb ωσπερει (hosperei), meaning wholly as if, just as it were (1 Corinthians 15:8 only).