Lacking in seriousness or importance. The committee dismissed his frivolous suggestions as they were not relevant to the discussion.
Carefree and not serious. She had a frivolous attitude towards her studies, preferring to spend her time socializing instead.
(Law) Of a claim, lawsuit, or appeal: having no serious purpose or merit and intended chiefly to delay, harass, or embarrass. The judge dismissed the frivolous lawsuit and sanctioned the attorney who filed it.