Teat-like; shaped like a nipple: specifically applied in anatomy to a part or process of the temporal bone, from its shape in man. See below.n. The mastoid part or process of the temporal bone: in adult man, a conical nipplelike bony prominence below and behind the orifice of the ear, to which the sternoclido-mastoid, trachelomastoid, digastric, and other muscles are attached, and which is grooved for the passage of the occipital artery.n. A distinct bone of the skull of some of the lower vertebrates, regarded by Owen as homologous with the mammalian mastoid.n. Same as pterotic.