Definition of silliness:
flapdoodle, flippancy, rubbish, fatuity, fiddle, folderol, blatherskite, crapola, insanity, light-mindedness, dippiness, bull, hogwash, nonsensicalness, tomfoolery, facetiousness, imbecility, drivel, nuts, bosh, taradiddle, punk, lightness, hoodoo, piffle, nerts, senselessness, fiddle-faddle, crock, stupidity, dizziness, tosh, horsefeathers, slush, absurdness, flightiness, daftness, guff, hooey, wackiness, trash, hokum, madness, ability, bunkum, balminess, dottiness, absurdity, trumpery, blather, giddiness, fatuousness, bunk, drool, tommyrot, beans, nuttiness, foolery, codswallop, malarkey, witlessness, fudge, moonshine, blarney, asininity, frothiness, zaniness, poppycock, lightheadedness, bilge, humbuggery, hokeypokey, flannel, applesauce, rot, fiddlesticks, blither, unwisdom, light-headedness, lunacy, twaddle, claptrap, vertigo, levity, simplicity, brainlessness, frivolousness, humbug, muck, garbage, blah, jazz.
absurdity (part of speech: noun)
- ridiculousness (part of speech: noun)
- "Since CÚzanne", Clive Bell.
- "The Upton Letters", Arthur Christopher Benson.
- "The Privet Hedge", J. E. Buckrose.