Mastoid

n. nipple-like projection; mastoid process of the temporal bone (Anatomy)

adj. resembling a breast; of the mastoid process; of or pertaining to the mastoid process of the temporal bone (Anatomy)

The mastoid process is a conical prominence projecting from the undersurface of the mastoid portion of the temporal bone. It is located just behind the external acoustic meatus, and lateral to the styloid process. Its size and form vary somewhat; it is larger in the male than in the female. This process serves for the attachment of the Digastric, Sternocleidomastoid, Splenius capitis, and Longissimus capitis muscles. The word is derived from the Greek 'masto-', alluding to its resemblance to the breast.
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Mastoid /mas·toid/ 1. breast-shaped. 2. mastoid process. 3. pertaining to the mastoid process. mas·toid n. The mastoid process. adj. 1. [more]Mastoid - Community and Resources

Noun
1. process of the temporal bone behind the ear at the base of the skull
(synonym) mastoid process, mastoid bone, mastoidal
(hypernym) process, outgrowth, appendage
(part-holonym) temporal bone, os temporale
(part-meronym) mastoidale
Adjective
1. relating to or resembling a nipple
(synonym) mastoidal
(pertainym) nipple, mammilla, mamilla, pap, teat, tit

(a.)
Resembling the nipple or the breast; -- applied specifically to a process of the temporal bone behind the ear.
  

(a.)
Pertaining to, or in the region of, the mastoid process; mastoidal.