non-return

non-re turn |ˌnänriˈtərn ˌnɑn rəˈtərn | ▶adjective Brit. permitting the flow of air or liquid in one direction only: a nonreturn valve.

non-return

non-return |ˈnɒnrɪtəːn | ▶adjective permitting the flow of air or liquid in one direction only: a non-return valve.

non-returnable

non-return ¦able ▶adjective (especially of a deposit ) not repayable or returnable in any circumstances. • denoting a bottle or other container that may not be returned empty to the supplier.