Beside is a preposition meaning “next to” (e.g., “Sit beside me”) or “compared to” (e.g., “My project seems amateur beside yours”). Besides is a preposition meaning “ in addition to ” or “other than” (e.g., “I have many goals besides graduating”). Definition of besides preposition in Oxford Advanced Learner's Dictionary. Meaning , pronunciation, picture, example sentences, grammar, usage notes, synonyms and more. Besides is a preposition or a linking adverb. It means ‘ in addition to ’ or ‘also’: … Do you play any other sports besides golf? He won’t mind if you’re late – besides, it’s not your fault. Besides nutrients and light, rice and weeds also competed for water. Besides definition: moreover; furthermore; also.. See examples of BESIDES used in a sentence.