shag [OE] Shag as in shag pile carpet was sceacga ‘rough matted hair’ in Old English. Of Germanic origin, it is related to Old Norse skegg ‘beard’. The mid 16th-century bird name shag is perhaps a specific use of the word, with reference to the bird’s ‘shaggy’ crest. The use of the verb to mean sexual intercourse is first recorded in 1770, but is probably older. It may go back to an older verb meaning ‘shake’ which is recorded between the 14th and 16th centuries.