Strong's Definition
probably from 408; nay, i.e. (softened) if
KJV Usage: but if, yea though
STEPBible — Tyndale Abridged Hebrew Lexicon
אִלּוּ (il.lu) — except. if, though (contrary to fact)
UBS Dictionary of Biblical Hebrew
UBS Dictionary of Biblical Hebrew © United Bible Societies, licensed CC BY-SA 4.0.
Brown-Driver-Briggs Hebrew Lexicon
אִלּוּ conj. if, though, only in late Heb. base