Uncouth is from Old English uncūth ('unknown, unfamiliar, strange'), from un- ('not') + cūth ('known, familiar'), past participle of cunnan ('to know'). The sense shifted from 'unfamiliar' to 'awkward, lacking grace'. Important recorded forms include uncūth (Old English), cūth (Old English), and *gnō- (Proto-Indo-European). Morphologically, the un- element marks negation, reversal, removal, or deprivation, while the base supplies the action, quality, or state being denied or undone. The semantic development is already visible in the history: an older concrete or specialized use was extended into the modern meaning rather than replaced by a separate origin. In current use it covers lacking good manners, refinement, or grace. The wider family includes derived forms such as uncouthly and uncouthness and related words such as couth.