n. (pl. -ies)
1. (often foll. by between, or disp. to, for) a spontaneous or natural liking for or attraction to a person or thing.
2 relationship, esp. by marriage.
3 resemblance in structure between animals, plants, or languages.
4 a similarity of characters suggesting a relationship.
5 Chem. the tendency of certain substances to combine with others.
Etymology: ME f. OF afinit{eacute} f. L affinitas -tatis f. affinis related, lit. bordering on (as AD- + finis border)