Search Result for "sacral vertebra":
Wordnet 3.0

NOUN (1)

1. one of 5 vertebrae in the human spine that fuse in the adult to form the sacrum; 



WordNet (r) 3.0 (2006):

sacral vertebra
    n 1: one of 5 vertebrae in the human spine that fuse in the
         adult to form the sacrum