Synonyms of silly in English:

silly


See definition of silly

adjective

1‘don't be so silly’

SYNONYMS
foolish, stupid, unintelligent, idiotic, brainless, mindless, witless, imbecilic, imbecile, doltish
imprudent, thoughtless, rash, reckless, foolhardy, irresponsible
mad, erratic, unstable, scatterbrained, feather-brained
flighty, frivolous, giddy, fatuous, inane, immature, childish, puerile, half-baked, empty-headed, half-witted, slow-witted, weak-minded
informal crazy, loopy, screwy, soft, brain-dead, cretinous, thick, thickheaded, birdbrained, pea-brained, pinheaded, dopey, dim, dim-witted, dippy, pie-faced, fat-headed, blockheaded, boneheaded, lamebrained, chuckleheaded, dunderheaded, wooden-headed, muttonheaded, damfool
British informal daft, dotty, scatty, divvy, dappy
Scottish, Northern English informal glaikit
North American informal dumb-ass, chowderheaded
South African informal dof
West Indian informal dotish
dated tomfool
ANTONYMS

sensible, rational

2‘that was a silly thing to do’

SYNONYMS
unwise, imprudent, thoughtless, foolish, stupid, idiotic, senseless, mindless, fatuous
rash, reckless, foolhardy, irresponsible, inadvisable, injudicious, ill-considered, misguided, inappropriate, illogical, irrational, unreasonable
hare-brained, absurd, ridiculous, ludicrous, laughable, risible, farcical, preposterous, asinine
informal crazy
British informal daft
ANTONYMS

sensible, rational

3‘he would brood about silly things’

SYNONYMS
trivial, trifling, frivolous, footling, petty, niggling, small, slight, minor, insignificant, unimportant, inconsequential, of little account
informal piffling, piddling
North American informal small-bore
ANTONYMS

important

4‘he often drank himself silly’

SYNONYMS
senseless, insensible, unconscious, stupid, dopey, into a stupor, into oblivion, into senselessness, into a daze
numb, dazed, stunned, stupefied, groggy, muzzy

noun

1‘come on, silly’

SYNONYMS
nincompoop, dunce, simpleton
informal nitwit, ninny, dimwit, dope, dumbo, dummy, chump, goon, jackass, fathead, bonehead, chucklehead, knucklehead, lamebrain, clod, pea-brain, pudding-head, thickhead, wooden-head, pinhead, airhead, birdbrain, scatterbrain, noodle, donkey
British informal silly billy, stupe, nit, clot, twit, berk, twerp
Scottish informal nyaff, sumph, gowk, balloon
North American informal bozo, boob, schlepper, goofball, goof, goofus, galoot, dumbhead, dumbass, lummox, dip, simp, spud, coot, palooka, poop, yo-yo, dingleberry
Australian, New Zealand informal drongo, dill, alec, galah, nong, bogan, poon, boofhead
South African informal mompara
informal, dated muttonhead, noddy
archaic clodpole, spoony, mooncalf