v. t. - 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.
v. t. - 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.
v. i. - To approach or meet in a common center; to consolidate; as, population tends to concentrate in cities.