barrator

[bar-uh-ter] /ˈbær ə tər/
noun, Law.
1.
a person who commits barratry.
Also, barrater, barretor.
Origin
1350-1400; Middle English barettour brawler, fighter < Anglo-French barretor, barator, Old French barateor, equivalent to barat(er) to make a disturbance, baret(er) to trick, cheat (< Vulgar Latin *prattāre < Greek prā́ttein to do, perform, manage; see practical) + -eor -ator
British Dictionary definitions for barrator

barrator

/ˈbærətə/
noun
1.
a person guilty of barratry
Word Origin
C14: from Old French barateor, from barater to barter