( especially BrE ) ( NAmE usually ˌone-on-ˈone ) adjective [ usually before noun ]
1.
between two people only :
a one-to-one meeting
2.
matching sth else in an exact way :
There is no one-to-one correspondence between sounds and letters.
► ˌone-to-ˈone adverb :
He teaches one-to-one.