- 1moving or allowing movement in only one direction one-way traffic a one-way street a one-way valve
- 2 a one-way ticket, etc. can be used for traveling to a place but not back again a one-way trip I took the car on a one-way trip to the wrecker's yard (= it did not come back because it was not worth fixing). compare round trip
- 3operating in only one direction Theirs was a one-way relationship (= one person made all the effort). They observed the prisoners through a one-way mirror (= a mirror that allows a person standing behind it to see through it).
[usually before noun]