An example of alas is someone saying they wish they'd known about an event before rsvp'ing for another, such as "Alas, I wish I would have known about the event because I have already agreed to go somewhere else."
Origin of alasMiddle English from Old French a las, helas from a-, he-, ah + las, wretched from Classical Latin lassus, weary
Origin of alasMiddle English from Old French a las, helas ah (I am) miserable from Latin lassus weary ; see lē- in Indo-European roots.
(plural alases or alasses)
From Yakut алаас (alaas).