(mathematics) Any function in which the interchange of two independent variables changes the sign of the dependent variable.

(geometry) the internal angles made by two (parallel) lines with a third, on opposite sides of it.

Any of various medical methods and practices used in place of, or as well as, conventional medicine.

(physics) An electric current in which the direction of flow of the electrons reverses periodically.

A voting system in which each voter lists the candidates in order of preference. At each stage the candidate with the fewest votes is excluded and their votes transferred according to the voters' preferences.

Any lifestyle generally perceived to be outside the norm of its culture. / (euphemistic, dated) Homosexuality, or other LGB identity or behavior.

(publishing, uncountable) Collectively, newspapers or other printed publications which provide an editorial perspective and information differing from—and often dissenting from—the outlook and information provided by more established, conventional, or official publications.

plural of alternative algebra

plural of alternating group

plural of alternative vote