bar·but 
(bär
b
ŭt
′) also
bar·bute (-by
t
′, -b
t
′) also
bar·bu·ta (-by
′t
ə, -b
′-)
n. A style of European helmet from the late Middle Ages, long on the sides and in back to protect the neck, and usually having a T-shaped opening in the front.
[French barbute, ultimately from Italian barbuta, from barba, beard (the helmet being so called because it allowed the wearer's beard to be seen), from Latin; see bhardh-ā- in the Appendix of Indo-European roots.]