What is "a feather in the cap"

Feather \Feath"er\ (f[e^][th]"[~e]r), n. [OE. fether, AS. fe[eth]er; akin to D. veder, OHG. fedara, G. feder, Icel. fj["o][eth]r, Sw. fj["a]der, Dan. fj[ae]der, Gr. ptero`n wing, feather, pe`tesqai to fly, Skr. pattra wing, feather, pat to fly, and prob. to L. penna feather, wing. [root]76, 248. Cf. Pen a feather.]

1. One of the peculiar dermal appendages, of several kinds, belonging to birds, as contour feathers, quills, and down.

   Note: An ordinary feather consists of the quill or hollow basal part of the stem; the shaft or rachis, forming the upper, solid part of the stem; the vanes or webs, implanted on the rachis and consisting of a series of slender lamin[ae] or barbs, which usually bear barbules, which in turn usually bear barbicels and interlocking hooks by which they are fastened together. See Down, Quill, Plumage.

2. Kind; nature; species; -- from the proverbial phrase, ``Birds of a feather,'' that is, of the same species. [R.]

   I am not of that feather to shake off My friend when he must need me.
   --Shak.

3. The fringe of long hair on the legs of the setter and some other dogs.

4. A tuft of peculiar, long, frizzly hair on a horse.

5. One of the fins or wings on the shaft of an arrow.

6. (Mach. & Carp.) A longitudinal strip projecting as a fin from an object, to strengthen it, or to enter a channel in another object and thereby prevent displacement sidwise but permit motion lengthwise; a spline.

7. A thin wedge driven between the two semicylindrical parts of a divided plug in a hole bored in a stone, to rend the stone.
   --Knight.

8. The angular adjustment of an oar or paddle-wheel float, with reference to a horizontal axis, as it leaves or enters the water. Note: Feather is used adjectively or in combination, meaning composed of, or resembling, a feather or feathers; as, feather fan, feather-heeled, feather duster. Feather alum (Min.), a hydrous sulphate of alumina, resulting from volcanic action, and from the decomposition of iron pyrites; -- called also halotrichite. --Ure. Feather bed, a bed filled with feathers. Feather driver, one who prepares feathers by beating. Feather duster, a dusting brush of feathers. Feather flower, an artifical flower made of feathers, for ladies' headdresses, and other ornamental purposes. Feather grass (Bot.), a kind of grass ( Stipa pennata) which has a long feathery awn rising from one of the chaffy scales which inclose the grain. Feather maker, one who makes plumes, etc., of feathers, real or artificial. Feather ore (Min.), a sulphide of antimony and lead, sometimes found in capillary forms and like a cobweb, but also massive. It is a variety of Jamesonite. Feather shot, or Feathered shot (Metal.), copper granulated by pouring into cold water. --Raymond. Feather spray (Naut.), the spray thrown up, like pairs of feathers, by the cutwater of a fast-moving vessel. Feather star. (Zo["o]l.) See Comatula. Feather weight. (Racing)

   1. Scrupulously exact weight, so that a feather would turn the scale, when a jockey is weighed or weighted.

   2. The lightest weight that can be put on the back of a horse in racing.
      --Youatt.

   3. In wrestling, boxing, etc., a term applied to the lightest of the classes into which contestants are divided; -- in contradistinction to light weight, middle weight, and heavy weight. A feather in the cap an honour, trophy, or mark of distinction. [Colloq.] To be in full feather, to be in full dress or in one's best clothes. [Collog.] To be in high feather, to be in high spirits. [Collog.] To cut a feather.

      1. (Naut.) To make the water foam in moving; in allusion to the ripple which a ship throws off from her bows.

      2. To make one's self conspicuous. [Colloq.]

         To show the white feather, to betray cowardice, -- a white feather in the tail of a cock being considered an indication that he is not of the true game breed.