one-way

Universal Words adjective [usuallybeforenoun] 1 moving or allowing movement in only one direction: one-way traffic * a one-way street * a one-way valve 2 (especially AmE) = SINGLE(5): 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). 3 operating 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).