Literary or humorous an expression of grief, pity, or concern
Alas, poor Yorick! I knew him, Horatio; a fellow of infinite jest, of most excellent fancy; he hath borne me on his back a thousand times; and now, how abhorred in my imagination it is!
Hamlet (V.i), William Shakespeare (1601)
The exclamation alas comes from the 13th century Old French expression ha, las, loosely meaning ‘how unfortunate’. In modern French, it has evolved into hélas; Dutch uses the similar helaas. The word las is derived from the Latin word lassus, meaning ‘tired’ or ‘weary’. The exclamation was originally used as an expression of weariness rather than woe.
The word late, which had the meaning of ‘slow’ or ‘sluggish’ in Old English, is related to alas in a way. Although originated from a Proto-Germanic word (*latas), late has the same Proto-Indo-European base as the Latin lassus: *lad-, meaning ‘slow’ or ‘weary’.