[mas.toid] adj [NL mastoides resembling a nipple, mastoid, fr. Gk mastoeides, fr. mastos breast] (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
[2]mastoid n (1842): a mastoid bone or process