Wiktionary
pentachloronitrobenzene
n. A fungicide formally derived from nitrobenzene; it is an off-white or yellow solid with a musty odour.
Wikipedia
Pentachloronitrobenzene
Pentachloronitrobenzene, typically abbreviated PCNB, is a registered fungicide formally derived from nitrobenzene. It is either an off-white or yellow solid, depending on its purity, with a musty odor.