\Hex"a*gram\, n. [Hexa- + -gram.]
A figure of six lines; specif.:
(a) A figure composed of two equal triangles intersecting so
    that each side of one triangle is parallel to a side of
    the other, and the six points coincide with those of a
    hexagon.
(b) In Chinese literature, one of the sixty-four figures
    formed of six parallel lines (continuous or broken),
    forming the basis of the Yih King, or ``Book of
    Changes.''