affinity

noun, plural af·fin·i·ties.

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.
6. Chemistry. the force by which atoms are held together in chemical compounds.

adjective

7. of or relating to persons who share the same interests: to arrange charter flights for opera lovers and other affinity groups.

noun plural -ties

1. (foll by with or for) a natural liking, taste, or inclination towards a person or thing
2. the person or thing so liked
3. a close similarity in appearance or quality; inherent likeness
4. relationship by marriage or by ties other than of blood, as by adoptionCompare consanguinity
5. similarity in structure, form, etc, between different animals, plants, or languages
6. chem
   1. the tendency for two substances to combine; chemical attraction
   2. a measure of the tendency of a chemical reaction to take place expressed in terms of the free energy changeSymbol: A
7. biology a measure of the degree of interaction between two molecules, such as an antigen and antibody or a hormone and its receptor

n.

c.1300, “relation by marriage” (as opposed to consanguinity), from Old French afinité (12c.), from Latin affinitatem (nominative affinitas) “neighborhood, relationship by marriage,” noun of state from affinis “adjacent,” also “kin by marriage,” literally “bordering on,” from ad- “to” (see ad-) + finis “a border, an end” (see finish). Used figuratively since c.1600 of structural relationships in chemistry, philology, etc. Meaning “natural attraction” (as though by family) is from 1610s.

n.

1. An attraction or force between particles that causes them to combine.
2. The attraction between an antigen and an antibody.
3. A relationship or resemblance in structure between species that suggests a common origin.
4. The selective staining of a tissue by a dye.
5. The selective uptake of a dye, chemical, or other substance by a tissue.

1. A relationship or resemblance in structure between species that suggests a common origin.
2. An attraction or force between particles that causes them to combine, as the attraction between an antigen and an antibody.