Peccant comes from the Latin verb peccare, which means "to sin," "to commit a fault," or "to stumble," and is related to the better-known English word peccadillo ("a slight offense"). Etymologists have suggested that peccare might be related to Latin ped- or pes, meaning "foot," by way of an unattested adjective, peccus, which may have been used to mean "having an injured foot" or "stumbling." Whether or not a connection truly exists between peccant and peccus,peccant itself involves stumbling of a figurative kind-making errors, for example, or falling into immoral, corrupt, or sinful behavior."
: causing disease
specific virtues…of drugs, as opposed to the unspecific adjustment of "peccant humours," were recognized in the 16th and 17th centuries— Joseph Needham