Synonyms for Bagatelle (same or very similar meaning)
WordNet sense 1 (something of little value or significance):
fluff, frippery, frivolityWordNet sense 2 (a table game in which short cues are used to knock balls into holes that are guarded by wooden pegs; penalties are incurred if the pegs are knocked over):
bar billiardsFrom the ODE community, based on WordNetadd/edit