noun

• (Ancient Rome, historical) A legally defined unit of Roman society, being a collection of people related through a common ancestor by birth, marriage or adoption, possibly over many generations, and sharing the same nomen gentilicium.
  "[page 568, column 2] There were certain sacred rites (sacra gentilitia) which belonged to a gens, to the observance of which all the members of a gens, as such, were bound, whether they were members by birth, adoption, or adrogation. A person was freed from the observance of such sacra, and lost the privileges connected with his gentile rites, when he lost his gens, that is, when he was adrogated, adopted, or even emancipated; for adrogation, adoption, and emancipation were accompanied by a diminutio capitis. […] [page 569, column 2] As the gentes were subdivisions of the three ancient tribes, the populus (in the ancient sense) alone had gentes, so that to be a patrician and to have a gens were synonymous; and thus we find the expressions gens and patricii constantly united."
• (anthropology) A tribal subgroup whose members are characterized by having the same descent, usually along the male line; clan.
  "The Kamilaroi are divided into six gentes, standing with reference to the right of marriage, in two divisions, […] Originally the first three gentes were not allowed to intermarry with each other, because they were subdivisions of an original gens; but they were permitted to marry into either of the other gentes, and vice versâ."
• (zoology) A host-specific lineage of a brood parasite species.^([W])