'Inion' definitions:

Definition of 'inion'

From: WordNet
noun
The craniometric point that is the most prominent point at the back of the head (at the occipital protuberance)

Definition of 'Inion'

From: GCIDE
  • Inion \In"i*on\, n. [NL., fr. Gr. 'ini`on the back of the head.] (Anat.) The external occipital protuberance of the skull. [1913 Webster]