Alas is an old exclamation of sorrow or regret. Alas, it was too late. Alas, no. Alas for the old days.
It is archaic and survives in poetry, in Shakespeare and in deliberately mannered modern use, where it is nearly always slightly playful: alas, the shop was shut. It appears at the start of a clause, followed by a comma. Note alack, its old companion, which is entirely dead; and that alas is one of the few genuinely obsolete words English speakers still recognise and enjoy.
1adverbalasAn old exclamation of sorrow or regret.
“Alas, the whole thing had been decided about a week earlier.”
alas is an exclamation of regret.
Old French a las means ah, weary — from Latin lassus, tired, the same root as lassitude. Alas is literally a sigh of exhaustion turned into a word.
Latin
lassus — weary
Old French
a las
Middle English
alas
English, today
alas
Built from
From Middle English alas, from Old French a las (French hélas), from a (“ah”) + las, from Latin lassus (“weary”). Compare Dutch helaas, frr ielas, West Frisian eilaas.
Etymology from Wiktionary, CC BY-SA