What is "piperonyl butoxide"

n. (context chemistry English) A pesticide synergist which increases the potency of other ingredients in the mix.

Piperonyl butoxide (PBO) is an organic compound used as a component of pesticide formulations. It is a waxy white solid. It is a synergist. That is, despite having no pesticidal activity of its own, it enhances the potency of certain pesticides such as carbamates, pyrethrins, pyrethroids, and rotenone. It is a semisynthetic derivative of safrole.