I. ˈmas-ˌtȯid adjective
Etymology: New Latin mastoides resembling a nipple, mastoid, from Greek mastoeidēs, from mastos breast
Date: 1732
1. : being the process of the temporal bone behind the ear ; also : being any of several bony elements that occupy a similar position in the skull of lower vertebrates
2. : of, relating to, or occurring in the region of the mastoid process
II. noun
Date: 1840
: a mastoid bone or process