Fermentation is a metabolic process that converts sugar to acids, gases, or alcohol. It occurs in yeast and bacteria, and also in oxygen-starved muscle cells, as in the case of lactic acid fermentation.
pupil noun [C] (EYE PART). âº the âcircular âblack âarea in the âcentre of an âeye, through which âlight âenters: Pupils âcontract in âbright âlight, and âdilate in darkness. (Definition of pupil from the Cambridge Advanced Learners Dictionary & Thesaurus Â© Cambridge University Press).
The apparently black circular opening in the center of the iris of the eye, through which light passes to the retina. [Middle English, from Old French. , from Latin. , little doll, pupil of the eye (from the tiny image reflected in it) ; see pupil 1 .].he apparently black circular opening in the center of the iris of the eye, through which light passes to the retina. [Middle English, from Old French. , from Latin. , little doll, pupil of the eye (from the tiny image reflected in it) ; see pupil 1 .].