—n. 1. a natural liking for or attraction to a person, thing, idea, etc.
2. a person, thing, idea, etc., for which such a natural liking or attraction is felt.
3. relationship by marriage or by ties other than those of blood (distinguished from consanguinity).
4. inherent likeness or agreement; close resemblance or connection.
5. Biol.the phylogenetic relationship between two organisms or groups of organisms resulting in a resemblance in general plan or structure, or in the essential structural parts.
6. Chem.the force by which atoms are held together in chemical compounds.
—adj. of or pertaining to persons who share the same interests: to arrange charter flights for opera lovers and other affinity groups.