Train Definition & Meaning - Merriam-Webster trained; training; trains transitive verb 1 a : to teach so as to make fit, qualified, or proficient b : to form by instruction, discipline, or drill 2 : to make prepared (as by exercise) for a test of skill 3 : to direct the growth of (a plant) usually by bending, pruning, and tying 4 : to aim at an object or objective : direct