An abbreviation of ‘optical art’, a form of abstract art which developed in the early 1960s and aimed at stimulation of the eye through a radical use of space and colour. This was achieved by the deployment of hard-edged, flatly painted shapes in black and white or in complementary colours of full intensity. The term ‘Op art’ was first used in Time magazine in 1964 and had become a household phrase by the following year when the defining exhibition The Responsive Eye was held at the Museum of Modern Art, New York.