uncouth (adj) - lacking manners or refinement; impolite, strange, or socially unacceptable [uhn-kooth]
couth means cultured or refined
couth as a noun means sophistication, polish, or good manners
BREAKDOWN: The word uncouth, which only a person with couth is likely to use, derives from the Old English uncūþ meaning unknown. Couth was the past tense of cunnan meaning to know. The shift in meaning from not known to not knowing manners or customs occurred over time and was solidly established by the 15th century.
See also: canny
“Within the oyster's shell uncouth
The purest pearl may hide,
Trust me you'll find a heart of truth
Within that rough outside.” —Frances Sargent Osgood
[Our Wednesday Wildcards are fascinating and important words that are not derived from classical roots.]