n. An artificial relationship between persons of different blood, regarded as analogous to consanguinity; the relation between families or individuals created by intermarriage (excluding that between the married persons), by legal adoption, or by sponsorship; more especially, the relation between a husband or wife and the kindred of the other spouse.n. Intercourse; acquaintance; companionship.n. Hence A natural liking for, or attraction to, a person or thing; a natural drawing or inclination; an inherent mutual liking or attraction.n. Inherent likeness or agreement as between things; essential or specific conformity; intimate resemblance or connection.n. In chem., that force by which the atoms of bodies of dissimilar nature unite in certain definite proportions to form a compound different in its nature from any of its constituents: called distinctively chemical or elective affinity.n. In biology, morphological and implied genetic relationship, resulting in a resemblance in general plan or structure, or in the essential structural parts, existing between two organisms or groups of organisms; true and near structural relationship, predicable of two or more organisms morphologically related, however diverse physiologically.n. In psychology, that in ideas which renders them capable of being associated in the mind, as their similarity or coadjacency.n. In geometry, the relationship between two figures in the same plane which correspond to each other, point to point and straight line to straight line, any point of the one lying in a fixed direction from the corresponding point of the other, and at a distance from it proportional to its distance from a fixed line, called the axis of affinity, the direction of which is that of lines joining corresponding points.n. In projective geometry, a perspective of which the center is at an infinite distance.