The Collaborative International Dictionary
Grobian \Gro"bi*an\, n. [G., fr. grob rude. Cf. Gruff, a.] A rude or clownish person; boor; lout.
Wiktionary
n. (context pejorative English) a coarse, uncouth, uncivilized fellow, perhaps violent
Wikipedia
Saint Grobian ( Medieval Latin, Sanctus Grobianus) was a fictional patron saint of vulgar and coarse people. His name is derived from the Middle High German grob or grop, meaning coarse or vulgar. The Old High German cognate is gerob, gerop.
The word "grobian" has thus passed into the English language as an obscure word for any crude, sloppy, or buffoonish person.
Usage examples of "grobian".
Be sure that he who is a Grobian in his own company, will, sooner or later, become a Grobian in that of his friends.
Porcupine was quite a Grobian but he was endowed, I was impressed, with a better brain than I.