Ma'anar ƙamus na kalmar "mastard agent" na nufin wani nau'in sinadari na yaƙi wanda aka samo daga gas ɗin mustard. Gas din mustard, wanda aka fi sani da sulfur mustard, ruwa ne marar launi, mai mai wanda ke haifar da kuna mai tsanani da blisters a fata da idanu, kuma yana iya haifar da lahani ga tsarin numfashi idan an shaka.An fara amfani da magungunan mustard. a matsayin makamin sinadari a lokacin Yaƙin Duniya na ɗaya, kuma tun daga lokacin an haramta shi a ƙarƙashin Yarjejeniyar Makamai Masu Guba ta 1993. Amfani da, haɓakawa, samarwa, da kuma tara abubuwan da ake amfani da su na mastad ana ɗaukarsa a matsayin babban cin zarafi ga dokokin ƙasa da ƙasa.