contra

(business) A deal to swap goods or services.

(politics, derogatory) A conservative; originally tied to Nicaraguan counter-revolutionaries.

(accounting, often attributive) An entry (or account) that cancels another entry (or account).

(music, informal) Any of the musical instruments in the contrabass range, e.g. contrabassoon, contrabass clarinet or, especially, double bass.

(dance) A contra dance.

(obsolete, US, New England, dance) A country dance.