n. In man, the hinder part of the head, or that part of the skull which forms the hind part of the head; the hindhead; the posterior part of the calvarium, from the middle of the vertex to the foramen magnum: opposed to sinciput.n. In other vertebrates, a corresponding but varying part of the head or skull: as, in most mammals, only that part corresponding to the supraoccipital bone itself, or from the occipital protuberance to the foramen magnum.n. In descriptive ornith., a frequent term for the part of the head which slopes up from nucha to vertex. See diagram under bird.n. In herpetology, the generally flat back part of the top of the head, as where, in a snake for example, the occipital plates are situated.n. In entomology, that part of the head behind the epicranium, belonging to the labial or second maxillary segment, and articulating with the thorax.