Affinity

1. noun

   (biology) state of relationship between organisms or groups of organisms resulting in resemblance in structure or structural parts

   “in anatomical structure prehistoric man shows close affinity with modern humans”

   Similar: phylogenetic relation

2. noun

   a close connection marked by community of interests or similarity in nature or character

   “found a natural affinity with the immigrants”

   Similar: kinship

3. noun

   the force attracting atoms to each other and binding them together in a molecule

   “basic dyes have an affinity for wool and silk”

   Similar: chemical attraction

4. noun

   (anthropology) kinship by marriage or adoption; not a blood relationship