Wordnet 3.0
NOUN (1)
1. 
 the craniometric point at the junction of the lamboid suture and the occipitomastoid suture and the parietomastoid suture; 
The Collaborative International Dictionary of English v.0.48:
Asterion \As*te"ri*on\, n. [Gr. 'aste`rion starry.] (Anat.)
   The point on the side of the skull where the lambdoid,
   parieto-mastoid and occipito-mastoid sutures.
   [1913 Webster]
WordNet (r) 3.0 (2006):
asterion
    n 1: the craniometric point at the junction of the lamboid
         suture and the occipitomastoid suture and the
         parietomastoid suture