1. The ordinal number matching the number one in a series.
2. The one coming, occurring, or ranking before or above all others.
3. The beginning; the outset: from the first; at first.
4. Music. The voice or instrument highest in pitch or carrying the principal part.
5. The transmission gear or corresponding gear ratio used to produce the range of lowest drive speeds in a motor vehicle.
6. The winning position in a contest: finished the season in first.
7. Baseball.
   1. First base.
   2. A first baseman.

1. Corresponding in order to the number one.
2. Coming before all others in order or location: the first house on your left.
3. Occurring or acting before all others in time; earliest: the first day of spring.
4. Ranking above all others, as in importance or quality; foremost: was first in the class.
5. Music. Being highest in pitch or carrying the principal part: first trumpet.
6. 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.
7. Of, related to, or being a member of the U.S. president's household: first daughter Amy Carter.

1. Before or above all others in time, order, rank, or importance: arrived first; forgot to light the oven first.
2. For the first time.
3. Rather; preferably: would die first.
4. In the first place; to begin with. See Usage Note at firstly.

first off (or thing)

1. From the start; immediately: Why wasn't I told first off? When I get to work, I have to call my lawyer first thing.

[Middle English, from Old English fyrst.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.