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.
Words nearby one-track mind
one-suiter,
one-tailed,
one-time,
one-to-one,
one-track,
one-track mind,
one-trick pony,
one-two,
one-up,
one-upmanship,
one-way