Music The voice or instrument highest in pitch or carrying the principal part. The transmission gear or corresponding gear ratio used to produce the range of lowest drive speeds in a motor vehicle. The winning position in a contest: finished the season in first. The ordinal number matching the number one in a series. The one coming, occurring, or ranking before or above all others. The beginning; the outset: from the first; at first. Baseball First base. Baseball A first baseman. Corresponding in order to the number one. Coming before all others in order or location: the first house on your left. Occurring or acting before all others in time; earliest: the first day of spring. Ranking above all others, as in importance or quality; foremost: was first in the class. Music Being highest in pitch or carrying the principal part: first trumpet. Of, relating to, or being the transmission gear or corresponding gear ratio used to produce the range of lowest drive speeds in a motor vehicle. Of, related to, or being a member of the U.S. president's household: first daughter Amy Carter. Before or above all others in time, order, rank, or importance: arrived first; forgot to light the oven first. For the first time. Rather; preferably: would die first. In the first place; to begin with. See Usage Note at firstly. off From the start; immediately: Why wasn't I told first off? When I get to work, I have to call my lawyer first thing.