affinity

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A natural attraction, liking, or feeling of kinship.
2. n. Relationship by marriage.
3. n. An inherent similarity between persons or things. See Synonyms at likeness.
4. n. Biology A relationship or resemblance in structure between species that suggests a common origin.
5. n. Immunology The attraction between an antigen and an antibody.
6. n. Chemistry An attraction or force between particles that causes them to combine.

Century Dictionary and Cyclopedia

1. 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. In the Jewish, Roman, and canon laws, affinity by marriage or adoption is a bar to marriage within certain degrees, equally with consanguinity; and on this ground rests the prohibition of marriage with a deceased wife's sister in Great Britain. The canon law treats unlawful sexual intercourse as creating the same affinity with marriage. The relationship of godparents and godchildren, called spiritual affinity, is not now considered a bar to marriage, as it was before the Council of Trent, which made no provision on the subject.
2. n. Intercourse; acquaintance; companionship.
3. n. Hence A natural liking for, or attraction to, a person or thing; a natural drawing or inclination; an inherent mutual liking or attraction.
4. n. Inherent likeness or agreement as between things; essential or specific conformity; intimate resemblance or connection.
5. 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. The word has lost its original meaning, and now signifies nothing more than chemical force. See chemical.
6. 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.
7. n. In psychology, that in ideas which renders them capable of being associated in the mind, as their similarity or coadjacency. The law of the affinity of ideas is another name for the law of continuity of notions, according to which two notions cannot be so similar but that it is possible to find a third intermediate between them.
8. 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.
9. n. In projective geometry, a perspective of which the center is at an infinite distance.

Wiktionary

1. n. A natural attraction or feeling of kinship to a person or thing.
2. n. A family relationship through marriage of a relative (e.g. sister-in-law), as opposed to consanguinity. (e.g. sister).
3. n. A kinsman or kinswoman of such relationship. Affinal kinsman or kinswoman.
4. n. The fact of and manner in which something is related to another.
5. n. Any romantic relationship.
6. n. Any passionate love for something.
7. n. taxonomy resemblances between biological populations; resemblances that suggest that they are of a common origin, type or stock.
8. n. geology structural resemblances between minerals; resemblances that suggest that they are of a common origin or type.
9. n. chemistry An attractive force between atoms, or groups of atoms, that contributes towards their forming bonds
10. n. medicine The attraction between an antibody and an antigen
11. n. computing tendency to keep a task running on the same processor in a symmetric multiprocessing operating system to reduce the frequency of cache misses

GNU Webster's 1913

1. n. Relationship by marriage (as between a husband and his wife's blood relations, or between a wife and her husband's blood relations); -- in contradistinction to consanguinity, or relationship by blood; -- followed by with, to, or between.
2. n. Kinship generally; close agreement; relation; conformity; resemblance; connection.
3. n. obsolete Companionship; acquaintance.
4. n. (Chem.) That attraction which takes place, at an insensible distance, between the heterogeneous particles of bodies, and unites them to form chemical compounds; chemism; chemical or elective affinity or attraction.
5. n. (Nat. Hist.) A relation between species or higher groups dependent on resemblance in the whole plan of structure, and indicating community of origin.
6. n. (Spiritualism) A superior spiritual relationship or attraction held to exist sometimes between persons, esp. persons of the opposite sex; also, the man or woman who exerts such psychical or spiritual attraction.

WordNet 3.0

1. n. a close connection marked by community of interests or similarity in nature or character
2. n. (anthropology) kinship by marriage or adoption; not a blood relationship
3. n. (biology) state of relationship between organisms or groups of organisms resulting in resemblance in structure or structural parts
4. n. the force attracting atoms to each other and binding them together in a molecule
5. n. inherent resemblance between persons or things
6. n. (immunology) the attraction between an antigen and an antibody
7. n. a natural attraction or feeling of kinship