NOUN (3)

1. (botany) a tiny outgrowth on the surface of a petal or leaf;

2. a small nipple-shaped protuberance concerned with taste, touch, or smell;
- Example: "the papillae of the tongue"

3. a small projection of tissue at the base of a hair or tooth or feather;

The Collaborative International Dictionary of English v.0.48:

Papilla \Pa*pil"la\, n.; pl. Papill[ae]. [L., a nipple,
   pimple.]
   Any minute nipplelike projection; as, the papill[ae] of the
   tongue.
   [1913 Webster]

WordNet (r) 3.0 (2006):

papilla
    n 1: (botany) a tiny outgrowth on the surface of a petal or leaf
    2: a small nipple-shaped protuberance concerned with taste,
       touch, or smell; "the papillae of the tongue"
    3: a small projection of tissue at the base of a hair or tooth
       or feather