noun (n)

• the base that must be touched first by a base runner in baseball(noun.artifact)

  source: wordnet30
• 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)(noun.act)

  Synonym:
  first
  

  source: wordnet30
• the initial stage in accomplishing something(noun.act)

  Example:
  We didn't get to first base with that approach.
  

  source: wordnet30