in fine fettle UK /ɪn ˌfaɪn ˈfɛtl̩/US /ɪn ˌfaɪn ˈfɛt(ə)l/ prepositional phrase1 •In good condition; energetic, fit.Tortoise: [Y]ou're looking in very fine fettle these days, I must say. Achilles: Thank you very much. — 1979