optics

n [sing v] scientific study of sight and of light in relation to it 光学.

opposite, opposition, oppress, oppress-ively, oppressed, oppression, oppressive, oppressor, opprobrious, opprobriously, opprobrium, ops, opt, opt out of, optic, optical, optical art, optical illusion, optically, optician, optimal, optimism, optimist, optimistic, optimistically, optimization, optimize, optimum, option, optional, optometrist, opulence, opulent, opus, or, or else, or rather, or so, oracle, oracular,