Eight (pl. ochos); Figure eights:
A crossing & pivoting figure from which the fan in American tango is derived. Executed as a walking step with flexed knees and feet together while pivoting, ochos may be danced either forward or backward and are so designated from the lady's perspective. El Ocho is considered to be one of the oldest steps in tango along with caminada, the walking steps. It dates from the era when women wore floor length skirts with full petticoats and danced on dirt floors. Since the lady's footwork could not be directly observed the quality of her dancing was judged by the figure she left behind in the dirt after she danced away.
(from batango.com (http://www.batango.com/Loomis.htm))
An Ocho is the basic figure that draws a pattern resembling an 8 on the floor (although normally done by the follower - it needn't be - the leader can do it too!). An Ocho Atrás is a Back Ocho; an Ocho Adelante is a Forward Ocho; an Ocho Doble is a Double Ocho; an Ocho Redondo is a Round Ocho; and a definite favourite: the Ocho Cortado is a Cut Ocho.
(from tangocanberra.asn.au (http://www.tangocanberra.asn.au/words.htm#Ocho))