glee: [OE] Glee has had a strange history. It was common in Old English times, both for ‘entertainment, having fun’ (source of the modern sense ‘joy, delight’), and in the more specific sense ‘musical entertainment’ (from which we get the ‘unaccompanied part-song’ of glee clubs). It survived healthily into the 15th century but then went into long-term decline. By the 17th century it seems virtually to have become extinct.
However, in 1755 Dr Johnson in his Dictionary said that it was ‘not now used except in ludicrous writing, or with some mixture of irony and contempt’, signalling the start of a revival which got fully under way towards the end of the 18th century. How and why it came back from the dead in this way is not known. Its source was Germanic *gliujam.
glee (n.)
Old English gliu, gliw, gleow "entertainment, mirth (usually implying music); jest, play, sport," also "music" and "mockery," presumably from a Proto-Germanic *gleujam but absent in other Germanic languages except for the rare Old Norse gly "joy;" probably related to the group of Germanic words in gl- with senses of "shining; smooth; radiant; joyful" (see glad). A poetry word in Old English and Middle English, obsolete c. 1500-c. 1700, it somehow found its way back to currency late 18c. In Old English, an entertainer was a gleoman (female gleo-mægden).
Glee club (1814) is from the secondary sense of "musical composition for three or more solo voices, unaccompanied, in contrasting movement" (1650s), a form of musical entertainment that flourished 1760-1830.