[pahy-per-uh-sil-in] 
| a broad-spectrum semisynthetic penicillin, C2 3H2 6N5NaO7, used against certain susceptible Gram-positive and Gram-negative bacteria and certain anaerobes, esp. P. aeruginosa. |
| piperacillin | |
noun | |
| a synthetic type of penicillin antibiotic (trade name Pipracil) used for moderate to severe infections |