Source : Webster's Revised Unabridged Dictionary (1913)

Acromion \A*cro"mi*on\, n. [Gr. ?; 'a`kros extreme + ? shoulder:
   cf. F. acromion.] (Anat.)
   The outer extremity of the shoulder blade.

Source : WordNet®

acromion
     n : the outermost point of the spine of the shoulder blade [syn:
          {acromial process}]
     [also: {acromia} (pl)]