parergon

 
Pronunciation: /pəˈrəːgɒn/

noun (plural parerga /-gə/)

formal
  • a piece of work that is supplementary to or a by-product of a larger work: the second sonata is a parergon to the opera
  • archaic work that is subsidiary to one’s ordinary employment: he pursued astronomy as a parergon

Origin:

early 17th century: via Latin from Greek parergon, from para- 'beside, additional' + ergon 'work'