Synonyms for Silly:

adj.

absurd (adjective)
absurd, anachronistic, bizarre, contradictory, crazy, eccentric, fallacious, farcical, foolish, goofy, idiotic, illogical, implausible, impossible, inane, incongruous, inconsistent, invalid, irrational, laughable, ludicrous, meaningless, nonsensical, outlandish, paradoxical, preposterous, ridiculous, self-contradictory, senseless.
absurd, giddy, foolish (adjective)
asinine, brainless, childish, crazy, dizzy, empty-headed, fatuous, featherbrained, flighty, frivolous, harebrained, idiotic, illogical, inane, inconsistent, irrational, ludicrous, meaningless, nonsensical, preposterous, puerile, ridiculous, senseless, unintelligent, unreasonable, vacuous, witless, dippy, simpleminded.
amusing (adjective)
comical.
capricious (adjective)
flighty.
foolish (adjective)
zany, cockamamy, imbecilic, tomfool, dippy.
ridiculous (adjective)
comical, curious, dubious, grotesque, incredible, laughable, oddball, outrageous, poppycock, weird, absurd, bizarre, crazy, eccentric, farcical, foolish, ludicrous, nonsensical, outlandish, preposterous, ridiculous.
senseless (adjective)
asinine, brainless, fatuous, harebrained, muddleheaded, puerile, shallow, trivial, vacuous, dippy, simpleminded, birdbrained, ditzy, air-headed.
softheaded (adjective)
softheaded.
unimportant (adjective)
inconsequential, irrelevant, mere, minor, petty, superficial, unconsidered, unimportant, of no consequence/of little consequence.
witless (adjective)
witless.

n.

annoying, exasperating, frustrating, infuriating, irritating, maddening, obscene, unbearable, vexing. ability, brainless, childish, fatuous, insensate, mindless, over-the-top, planned, unintelligent, witless, Weak-minded, not in your right mind/not right in the head. dopey, harebrained, imbecilic, insane, jerky, knowledge, lunatic, mad, moronic, simple-minded, slow, slow-witted, softheaded, thick, tomfool, unearthly, dippy. bang, big, birdie, boo-boo, bow-wow, bunny, choo-choo, cold, cross, flighty, frothy, gaga, lighthearted, scatterbrained, birdbrained. innuendo, joke, one-liner, pun, punch line, wisecrack, witticism, wordplay, a play on words. fool (noun)
fool.
silly (noun)
airheaded, cockamamie, cockamamy, confused, dizzy, empty-headed, featherbrained, fool, foolish, frivolous, giddy, goofy, light-headed, lightheaded, pathetic, punch-drunk, ridiculous, sappy, slaphappy, undignified, unreasonable, wacky, whacky, zany.

Other synonyms:

brainless, fatuous, gaga, jerky, over-the-top, simple-minded, slow-witted, softheaded, witless, dippy, birdbrained. childish, harebrained, mindless, moronic, scatterbrained, shallow, unintelligent, Weak-minded. dopey, lunatic. frothy, insane, insensate, lighthearted, unearthly. mad. slow. thick. giddy
giddy.
imbecile
imbecilic.
punch-drunk
punch-drunk.
silly
asinine.
Other relevant words:
ability, airheaded, annoying, asinine, bang, big, birdie, boo-boo, bow-wow, brainless, bunny, childish, choo-choo, cockamamie, cockamamy, cold, confused, cross, dizzy, dopey, empty-headed, exasperating, fatuous, featherbrained, flighty, fool, frivolous, frothy, frustrating, gaga, giddy, goofy, harebrained, imbecilic, inconsequential, infuriating, innuendo, insane, insensate, irrelevant, irritating, jerky, joke, knowledge, light-headed, lightheaded, lighthearted, lunatic, mad, maddening, mere, mindless, minor, moronic, muddleheaded, obscene, one-liner, over-the-top, pathetic, petty, planned, puerile, pun, punch-drunk, sappy, scatterbrained, shallow, simple-minded, slaphappy, slow, slow-witted, softheaded, superficial, thick, tomfool, trivial, unbearable, unconsidered, undignified, unearthly, unimportant, unintelligent, unreasonable, vacuous, vexing, wacky, whacky, wisecrack, witless, witticism, wordplay, zany, Weak-minded, dippy, simpleminded, birdbrained, ditzy.

Usage examples for silly

  1. Do all girls talk such silly nonsense? – Secret Bread by F. Tennyson Jesse
  2. " That's a very silly thing to say," I told him. – Here and Hereafter by Barry Pain
  3. But sometimes I am a little anxious about him- I know it's silly of me. – The Dark Tower by Phyllis Bottome