AFFINITY

[noun]

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. Biology: 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.

[adjective]

6. of or pertaining to persons who share the same interests.

Etymology: Middle English affinite < Middle French < Latin affīnitās - connection by marriage.