From Longman Dictionary of Contemporary Englishone-on-oneˌone-on-ˈone adjective between only two people Virtually all instruction is in small groups or one-on-one. —one-on-one adverb Often, the employer just called in the drivers and bargained with them directly, one-on-one.
Examples from the Corpus
one-on-one• Kids need one-on-one attention. 