op art

(also optical art) form of modern abstract art using geometrical patterns that produce optical illusions 光效应艺术（利用几何图形产生视幻觉的抽象艺术）.

onomatopoeia, onomatopoeic, onrush, onset, onshore, onside, onslaught, onto, onto (also on to), ontological, ontology, onus, onward, onward(s), onyx, oodles, oomph, ooze, op, op (also Op), op-ed, opacity, opague, opal, opalescence, opalescent, opaque, opaquely, opaqueness, OPEC, open, open an account, open cheque, open day, open letter, open out, open prison, open question, open sandwich, open to,