Meaning of labellum

la•bel•lum

Pronunciation: (lu-bel'um), [key]
— pl. -bel•la
  1. the petal of an orchid that differs more or less markedly from the other petals, often forming the most conspicuous part; the lip.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.