Definition

four

A figure created when the lady flicks her lower leg up the outside of the opposite leg, keeping her knees together, and briefly creating a numeral 4 in profile. This can be led with a sacada or with an arrested rotational lead like a boleo, or it can be used, at the lady’s discretion, in place of a gancho or as an adornment after a gancho.

See Amague

(from tangoafficionado.com (http://www.tangoafficionado.com/tango_terminology.htm))