Google Definition: A ballroom dance of Latin American origin in ²/₄ time with a basic pattern of step-step-step-step-close and characterized by long pauses and stylized body positions. 

Artist Definition: One of the most fascinating of all dances, the tango is a sensual ballroom dance that originated in Buenos Aires, Argentina in the early XX century.

(Continuation of Artist Definition): The tango dance is usually performed by a man and a woman, expressing an element of romance in their synchronized movements. Originally, the tango was performed only by women, but once it spread beyond Buenos Aires, it developed into a dance for couples. 

Taken from Treva Bedinghaus 

Refreshing the Tango