Real Dictionary

vegetarian
adjective: Someone who is vegetarian never eats meat or fish.

vegetarian in American English
a person who eats no meat, and sometimes no animal products (as milk or eggs); esp., one who advocates a diet of only vegetables, fruits, grains, and nuts as the proper one for all people for reasons of health or because of principles opposing the killing
of vegetarians or vegetarianism
adjective: of or pertaining to vegetarianism or vegetarians
noun: a person who does not eat or does not believe in eating meat, fish, fowl, or, in some cases, any food derived from animals, as eggs or cheese, but subsists on vegetables, fruits, nuts, grain, etc

vegetarian in British English
adjective: relating to, advocating, or practising vegetarianism
noun: a person who advocates or practises vegetarianism