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Phrase(s): in fine feather
1. Fig. well dressed; of an excellent appearance. (Alludes to a bird that has clean, bright, and flawless feathers.) • Well, you are certainly in fine feather today. • I like to be in fine feather when I have to give a speech. 2. Fig. in good form; in good spirits. • Mary was really in fine feather tonight. Her concert was great! • I feel in fine feather and ready to go!
McGrawhill's American Idioms And Phrasal Verbs
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Also, in good or high feather. In excellent form, health, or humor. For example, He was in fine feather, joking with all his visitors. These expressions all allude to a bird's healthy plumage, a usage dating from the late 1500s and no longer very common.
American Heritage Idioms