Strong's 1437 (ἐάν)

before, but, except, (and) if, (if) so, (what-, whither-)soever, though, when (-soever), whether (or), to whom, (who-)so(-ever)

a conditional particle; in case that, provided, etc.; often used in connection with other particles to denote indefiniteness or uncertainty

from G1487 (εἰ) and G302 (ἄν);