Answer: "Termagant," supposed to have been a god of the
Saracens, a very violent character, was employed very often
in the plays of the middle ages, but no such character has
been found in any English plays. The Italian is Trivigante.
Derivation probably ter, three, and magnus, great.
Herod was also a favorite character of the time, very noisy
and turbulent, hence to "out-herod Herod" would be to be
excessively violent.
Mertins, Emma. Shakespeare Examinations. Ed. William Taylor Thom, M. A. Boston: Ginn and Co., 1888. Shakespeare Online. 10 Aug. 2010. (date when you accessed the information) < http://www.shakespeare-online.com/plays/hamlet/examq/eighteen.html >.