penicilloic acid

noun

pen·​i·​cil·​lo·​ic acid ˌpen-ə-sə-ˌlō-ik- 

: any of several acids having the general formula RCONH(C₆H₁₀NS)(COOH)₂ which are obtained from the penicillins by hydrolytic opening of the lactam ring (as by the action of a beta-lactamase)