To be of no help or use to someone; to fail to benefit or assist.
From dis- (prefix meaning 'not') + avail (from Old French valoir, 'to be strong' or 'to be worth'). The word is archaic and rare in modern English.
This is an old English word that means 'to not help'—but we've replaced it with simpler phrases like 'to no avail' or 'it didn't help.' It shows how language evolves by dropping longer verbs in favor of shorter phrases.
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