Source : Webster's Revised Unabridged Dictionary (1913)

Antenna \An*ten"na\, n.; pl. {Antenn[ae]}. [L. antenna
   sail-yard; NL., a feeler, horn of an insect.] (Zo["o]l.)
   A movable, articulated organ of sensation, attached to the
   heads of insects and Crustacea. There are two in the former,
   and usually four in the latter. They are used as organs of
   touch, and in some species of Crustacea the cavity of the ear
   is situated near the basal joint. In insects, they are
   popularly called horns, and also feelers. The term in also
   applied to similar organs on the heads of other arthropods
   and of annelids.

Source : WordNet®

antenna
     n 1: an electrical device that sends or receives radio or
          television signals [syn: {aerial}, {transmitting aerial}]
     2: sensitivity similar to that of a receptor organ; "he had a
        special antenna for public relations" [syn: {feeler}]
     3: one of a pair of mobile appendages on the head of e.g.
        insects and crustaceans; typically sensitive to touch and
        taste [syn: {feeler}]
     [also: {antennae} (pl)]