To begin an activity or a movement; set out. To have a beginning; commence. See Synonyms at begin. To move suddenly or involuntarily: started at the loud noise. To come quickly into view, life, or activity; spring forth. Sports To be in the initial lineup of a game or race. To protrude or bulge. To become loosened or disengaged. To commence; begin. To set into motion, operation, or activity. To introduce; originate. Sports To play in the initial lineup of (a game). Sports To put (a player) into the initial lineup of a game. Sports To enter (a participant) into a race or game. To found; establish: start a business. To tend in an early stage of development: start seedlings. To rouse (game) from its hiding place or lair; flush. To cause to become displaced or loosened. A beginning; a commencement. The beginning of a new construction project: an application for a building start. A place or time of beginning. Sports A starting line for a race. Sports A signal to begin a race. Sports An instance of beginning a game or race: a pitcher who won his first five starts. A startled reaction or movement. A part that has become dislocated or loosened.