bias

the angle line bisecting the angle between the two grain lines of the fabric. the bias line runs diagonally across the grain; it has maximum give and stretch and easily conforms to a figure's contours. the aesthetic quality of flares, cowls, and drapes is best when cut on the bias. any diagonal angle line across the grain of the fabric may be referred to by the term "bias", in which case the angle line bisecting the angle between the two grain lines is specified by the qualifier "true".