Hypostome

Noun

1. Any of certain mouth appendages of some insects, arachnids, crustaceans, and hydrozoa; in particular: The ventral mouthpart plate in trilobites; The barbed attachment structure associated with the mouthparts of parasitic arachnids (e.g. ticks); The oral tip surrounded by tentacles in hydrozoan cnidarians.
2. The ventral mouthpart plate in trilobites;
3. The barbed attachment structure associated with the mouthparts of parasitic arachnids (e.g. ticks);
4. The oral tip surrounded by tentacles in hydrozoan cnidarians.