Source : Webster's Revised Unabridged Dictionary (1913)

Petronel \Pet`ro*nel\, n. [OF. petrinal, fr. peitrine, petrine,
   the breast, F. poitrine; so called because it was placed
   against the breast in order to fire. See {Poitrel}.]
   A sort of hand cannon, or portable firearm, used in France in
   the 15th century.