reciprocity

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A reciprocal condition or relationship.
2. n. A mutual or cooperative interchange of favors or privileges, especially the exchange of rights or privileges of trade between nations.

Century Dictionary and Cyclopedia

1. n. Reciprocal action or relation; free interchange; mutual responsiveness in act or effect: as, reciprocity of benefits or of feeling; reciprocity of influence.
2. n. Equality of commercial privileges between the subjects of different, governments in each other's ports, with respect to shipping or merchandise, to the extent established by treaty.
3. n. In the Kantian philosophy, mutual action and reaction in the strict, mechanical sense.
4. n. In geom., the mutual relationship between points and straight lines in a plane, or points and planes in space, etc.; duality.
5. n. the proposition that the number of invariants of the nth order in the coefficients possessed by a binary quautic of the pth degree is equal to the number of invariants of the order p in the coefficients possessed by a quantic of the nth degree.
6. n. Synonyms Exchange, interchange, reciprocation.

Wiktionary

1. n. the characteristic of being reciprocal, e.g. of a relationship between people
2. n. a reciprocal relationship
3. n. a relation of mutual dependence or action or influence
4. n. the mutual exchange of rights, privileges or obligations between nations
5. n. psychology the responses of individuals to the actions of others

GNU Webster's 1913

1. n. Mutual action and reaction.
2. n. Reciprocal advantages, obligations, or rights; reciprocation.

WordNet 3.0

1. n. a relation of mutual dependence or action or influence
2. n. mutual exchange of commercial or other privileges