mid-13c., from Old French ha, las (later French hélas), from ha "ah" + las "unfortunate," originally "tired, weary," from Latin lassus "weary" (from PIE root *lē- "to let go, slacken"). At first an expression of weariness rather than woe.
alas, I cannot stay
alarm
alarmed
alarmingly
alarmist
alarum
alas
Alaska
alastor
alate
alb
albacore