Longman Dictionary of Contemporary English - weed

~1 n 1 a wild plant growing where it is not wanted and that prevents crops or garden flowers from growing properly 2 a plant without flowers that grows on water in a large green floating mass 3 BrE informal someone who is weak  (Nigel's such a weed, isn't he?) 4 the weed informal cigarettes or tobacco 5 old-fashioned cannabis 6 (widow's) weeds old use black clothes worn by a woman whose husband has died ~2 v to remove unwanted plants from a garden or other place weed sb/sth out phr v to get rid of people or things that are not very good  (Unsuitable recruits were soon weeded out.)