1. to begin to have success with something that you want to do.

They won't even get to first base with the directors with a proposal like that.

2. to get to the first stage of a sexual relationship, where partners kiss and touch each other.

Jimmy hasn't even gotten to first base yet with his girlfriend.

• one-day wonder
• on edge
• one for the books
• one for the road
• One good turn deserves another.
• one-hit wonder
• one-horse race
• one-horse town
• one-man band
• One man's meat is another man's poison.
• on end
• one-night stand
• one of a kind
• one of the boys
• one of the lads
• one of those days
• one-shot
• one step ahead
• One step forward, two steps back.
• one swallow doesn't make a summer
• one thing after another
• one thing leads to another
• one-to-one
• one-two punch
• one-upmanship