Cox-1 cox uncommon noun 1. an enzyme that regulates prostaglandins that are important for the health of the stomach lining and kidneys “an unfortunate side effect of Nsaids is that they block Cox-1” Synonymscyclooxygenase-1 Related words Broader terms cyclooxygenase WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.