From the ArcaMax Publishing, Vocabulary Newsletter:
http://www.arcamax.com/news/vocabulary/s-371082-723663
peccant \PEK-unt\ (adjective) - 1 : Sinning; guilty of transgression.
2 : Violating a rule or a principle.
"It is allowed, that Senates and great Councils are often troubled
with redundant, ebullient, and other peccant Humours..." -- Jonathan
Swift, 'Gulliver's Travels'
Peccant comes from the present participle of Latin of peccare, "to
sin."