
 A birrus or birrus brittanicus was a rainproof, hooded woollen cloak (or simply a hood alone), characteristically worn in Britain and Gaul at the time of the Roman Empire and into the Middle Ages. A mosaic at Chedworth Roman Villa shows a Briton wearing a birrus brittanicus there is also one shown on a statue of a ploughman at the British Museum. ...
Found on 
http://en.wikipedia.org/wiki/Birrus

• (n.) A coarse kind of thick woolen cloth, worn by the poor in the Middle Ages; also, a woolen cap or hood worn over the shoulders or over the head.
Found on 
http://thinkexist.com/dictionary/meaning/birrus/
Bir'rus  noun [ Late Latin , from Latin 
 birrus a kind of cloak. See 
 Berretta .] A coarse kind of thick woolen cloth, worn by the poor in the Middle Ages; also, a woolen cap or hood worn over the shoulders or over the head. 
Found on 
http://www.encyclo.co.uk/webster/B/56

a hooded cloak of coarse wool, a common article of apparel in the later Roman Empire.
Found on 
https://www.infoplease.com/dictionary/birrus
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