Concentrate

Webster's Dictionary of the English Language

·vi To approach or meet in a common center; to Consolidate; as, population tends to concentrate in cities.

II. Concentrate ·vt To bring to, or direct toward, a common center; to unite more closely; to gather into one body, mass, or force; to Fix; as, to concentrate rays of light into a focus; to concentrate the attention.

III. Concentrate ·vt To increase the strength and diminish the bulk of, as of a liquid or an ore; to intensify, by getting rid of useless material; to Condense; as, to concentrate acid by evaporation; to concentrate by washing;

— opposed to dilute.