optical

a.光学的；视觉的，视力的

opportunist, opportunistic, opportunity, oppose, opposed, opposite, opposition, oppress, oppress-ively, oppressed, oppression, oppressive, oppressor, opprobrious, opprobriously, opprobrium, ops, opt, opt out of, optic, optical art, optical illusion, optically, optician, optics, optimal, optimism, optimist, optimistic, optimistically, optimization, optimize, optimum, option, optional, optometrist, opulence, opulent, opus, or,