EXPEDITION definition: 1. an organized journey for a particular purpose: 2. the people, vehicles, animals, etc. taking…. Learn more. Definition of expedition. English dictionary and integrated thesaurus for learners, writers, teachers, and students with advanced, intermediate, and beginner levels. The meaning of EXPEDITION is a journey or excursion undertaken for a specific purpose. How to use expedition in a sentence. Synonym Discussion of Expedition. See our expert review on the 2025 Ford Expedition and where it ranks among other large SUVs. Research the ratings, prices, pictures, MPG and more.