Source : Webster's Revised Unabridged Dictionary (1913)

Papilla \Pa*pil"la\, n.; pl. {Papill[ae]}. [L., a nipple,
   pimple.]
   Any minute nipplelike projection; as, the papill[ae] of the
   tongue.

Source : WordNet®

papilla
     n 1: a small nipple-shaped protuberance concerned with taste,
          touch, or smell; "the papillae of the tongue"
     2: a small projection of tissue at the base of a hair or tooth
        or feather
     [also: {papillae} (pl)]