Definition of the missionary position noun in Oxford Advanced Learner's Dictionary. Meaning , pronunciation, picture, example sentences, grammar, usage notes, synonyms and more. MISSIONARY POSITION meaning : 1. a position for having sex in which a woman lies on her back and her partner is above and facing…. Learn more. Missionary position definition : a face-to-face sex position in which the person who is being penetrated lays flat on their back, while the person who is penetrating them lays on top of them.. See examples of MISSIONARY POSITION used in a sentence. Definition of missionary position . English dictionary and integrated thesaurus for learners, writers, teachers, and students with advanced, intermediate, and beginner levels.