'first base' definitions:
Definition of 'first base'
(from WordNet)
noun
The base that must be touched first by a base runner in baseball
noun
The fielding position of the player on a baseball team who is stationed at first of the bases in the infield (counting counterclockwise from home plate) [syn: first base, first]
noun
The initial stage in accomplishing something; "we didn't get to first base with that approach"