Noun
one track mind (plural one track minds)
Alternative spelling of one-track mind
one-track mind (plural one-track minds)
(idiomatic) That said to be possessed by someone who is obsessed with something or only able to think of one thing.
Synonyms: see Thesaurus:obstinacy
He has a one-track mind. All he ever talks about is trains and railroads.
one-track mind