A Venefica was a Roman sorceress who used drugs, potions, and poison for several reasons. Venefica means "a female who poisons" in Latin. Veneficus was the masculine form.

The word appears in Roman authors such as Cicero and Horace. Ovid uses it of Medea the sorceress in his Metamorphoses. Later it appears in one of Sir Francis Bacon's Essays,"Of Friendship" in the following lines:

"And it seemeth his favour was so great, as Antonius, in a letter which is recited verbatim in one of Cicero’s Philippics, calleth him ‘venefica,’ witch, —as if he had enchanted Caesar."

• Witchvox article with section on Venefica (archived)
• Meaning of the name Venefica
• Raven Grimassi examines the term Venefica in witchcraft