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English definition of “mastoid”

mastoid

adjective uk   /ˈmæs.tɔɪd/ specialized us  
relating to the mastoid process (= part of the skull just behind the ear): Mastoidectomy is performed to remove infected air cells within the mastoid bone.
shaped like a breast or a nipple ( =the small dark part that sticks out from the breast)
(Definition of mastoid from the Cambridge Advanced Learners Dictionary & Thesaurus © Cambridge University Press)
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