a focus on one issue or topic, to the exclusion of all else; an obsession with one thing
Examples
She just has a one-track mind, wanting to move on.
Word Origin
1938; fr. railways
Slang definitions & phrases for one-track mind
one-track mind
noun phrase
A mind limited to or obsessed with a single idea, theme, etc (1927+)
Idioms and Phrases with one-track mind
one-track mind
A mind limited to only one line of thought or action, as in All you think about is sex—you have a one-track mind. This expression, alluding to a train that runs only on one track or in one direction, was first recorded in 1928.