Search Result for "omicron": 
Wordnet 3.0

NOUN (1)

1. the 15th letter of the Greek alphabet; 



The Collaborative International Dictionary of English v.0.48:

Omicron \O*mi"cron\, n. [Written also omikron.] [NL., fr. Gr.
   [Omicron] [omicron]. See Micro-.]
   Lit., the little, or short, O, o; the fifteenth letter of the
   Greek alphabet.
   [Webster 1913 Suppl.]


WordNet (r) 3.0 (2006):

omicron
    n 1: the 15th letter of the Greek alphabet