concThe word which today can be considered part of the MSA vocabulary, is originally a word from the SyrAr dialect that entered the Language via Aram ʔelūlā, lHbr ʔälûl, and ultimately goes back to Akk elūlu, name of a month (Nişanyan2011: ‘harvest season’).
This latter is probably connected to the vb. Akk elēlu (< *ḥalālum) ‘to be(come) clean, pure, holy’ which belongs to the Sem root *ḤLL, cf. Ar ↗ḤLː (ḤLL), ↗ḥalla (ḥall), ↗ḥalla (ḥill), ↗ḥalla (ḥull).