codpiece

noun /ˈkɒdˌpiːs/

a) A part of male dress in front of the breeches to cover the male genitals, sometimes made very conspicuous in former times.

Borachio: Seest thou not, I say, what a deformed thief this fashion is, how giddily ’a turns about all the hot-bloods between fourteen and five-and-thirty, sometimes fashioning them like Pharaoh’s soliders in the reechy painting, sometime like god Bel’s priests in the old church-window, sometime like the shaven Hercules in the smirch’d worm-eaten tapestry, where his codpiece seems as massy as his club?

b) A conspicuous protection for the male genitals in a suit of plate armor.

On some suits were screwed large iron cod-pieces; these, according to tradition, were intended to prevent the ill consequences of those violent shocks received in charging, either in battle, or at a tournament. Same say, they were meant to contain sponges for receiving the water of knights, who in the heat of an engagement might not have any more convenient method of discharging it. But most probably, they were rather constructed in conformity to a reigning fashion in the make of the breeches of those times.