The mastoid process.
1. Of or relating to the mastoid process.
2. Shaped like a breast or nipple.
[New Latin mastoīdēs, nipple-like, mastoid (from its shape), from Greek mastoeidēs : mastos, breast + -oeidēs, -oid.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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