Affixes

This ending appears in some specialist words in zoology for animals with certain kinds of mouths, as in cyclostome, an eel-like jawless vertebrate with a circular sucking mouth, such as a lamprey or hagfish; protostome (Greek proto‑, primitive), a multicellular organism whose mouth develops from a primary embryonic opening, such as a mollusc or arthropod; the peristome (Greek peri‑, around) is the part surrounding the mouth of various invertebrates. Such nouns have associated adjectives in ‑stomous, such as physostomous (Greek physa, bladder), having the mouth and air bladder connected by an air duct. See also ‑tome.