first base

nouns

the base that must be touched first by a base runner in baseball

first base

is a type of (narrower)

a place that the runner must touch before scoring

"he scrambled to get back to the bag"

bag, base

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)

first, first base

the initial stage in accomplishing something

"we didn't get to first base with that approach"

first base

is a type of (narrower)

the first of a series of actions

first step, initiative, opening, opening move