Definition of besides preposition in Oxford Advanced Learner's Dictionary. Meaning , pronunciation, picture, example sentences, grammar, usage notes, synonyms and more. Besides (with an ‘s’) has various meanings including ‘except’, ‘as well as’, and ‘furthermore’ . Unlike ‘beside’, it doesn’t refer to literal physical proximity. 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”). Besides definition: moreover; furthermore; also.. See examples of BESIDES used in a sentence.