- (transitive) To figure out the answer to (a riddle).
- (transitive, by extension) To solve (a perplexing problem).
1749, Henry Fielding, The History of Tom Jones, a Foundling, London: A[ndrew] Millar, OCLC 928184292:
- “I your enemy, sir!” says he, with much amazement, and some sternness in his look. “Nay, be not angry,” said Benjamin, “for I promise you I am not. You are perfectly innocent of having intended me any wrong; for you was then an infant: but I shall, I believe, unriddle all this the moment I mention my name. Did you never hear, sir, of one Partridge, who had the honour of being reputed your father, and the misfortune of being ruined by that honour?”