Source : Webster's Revised Unabridged Dictionary (1913)

Seta \Se"ta\, n.; pl. {Set[ae]}. [L. seta, saeta, a bristle.]
   1. (Biol.) Any slender, more or less rigid, bristlelike organ
      or part; as the hairs of a caterpillar, the slender spines
      of a crustacean, the hairlike processes of a protozoan,
      the bristles or stiff hairs on the leaves of some plants,
      or the pedicel of the capsule of a moss.

   2. (Zo["o]l.)
      (a) One of the movable chitinous spines or hooks of an
          annelid. They usually arise in clusters from muscular
          capsules, and are used in locomotion and for defense.
          They are very diverse in form.
      (b) One of the spinelike feathers at the base of the bill
          of certain birds.

Source : WordNet®

seta
     n 1: stalk of a moss capsule
     2: a stiff hair or bristle
     [also: {setae} (pl)]

setae
     See {seta}