|a. the base that a runner must reach safely to score a hit, and the first of the three bases he must reach safely on the way to home plate in order to score a run|
|b. the fielding position nearest this base|
|2.||informal chiefly (US), (Canadian) get to first base to accomplish the first step of an undertaking|
get to first base
Also, reach first base.
Succeed in the initial phase of something; meet with preliminary approval. For example, They were delighted that they'd gotten to first base in the negotiations. This term alludes to the first base of baseball, which is the first step toward scoring a run for the batter's team. [c. 1900]
Reach the initial stage of sexual intimacy, such as kissing. For example, Mary is so shy that I can't even get to first base with her. [1920s]