Indicating a lack of maturity:
— Childish tantrums.

synonym: infantile.

Roget 575: feeble, bald, tame, meager, jejune, vapid, bland, trashy, lukewarm, cold, frigid, poor, dull, dry, languid; colorless, enervated; proposing, prosy, prosaic; unvaried, monotonous, weak, washy, wishy-washy; sketchy, slight.    careless, slovenly, loose, lax (negligent) 460; slipshod, slipslop^†; inexact; puerile, childish; flatulent; rambling etc. (diffuse) 573.    ... show more

Roget 499: unintelligent [Applied to persons], unintellectual, unreasoning; mindless, witless, reasoningless^†, brainless; halfbaked; having no head etc. 498; not bright etc. 498; inapprehensible^†.    weak headed, addle headed, puzzle headed, blunder headed, muddle headed, muddy headed, pig headed, beetle headed, buffle headed^†, chuckle headed, mutton headed, maggoty headed, grossheaded^†; beef headed, fat witted, fat-headed.    weak-minded, feeble-minded; dull minded, shallow minded, lack-brained; rattle-brained, rattle headed; half witted, lean witted, short witted, dull witted, blunt-witted, shallow-pated^†, clod-pated^†, addle-pated^†, addle-brained^†; dim-sighted, short-sighted; thick-skulled; weak in the upper story.    shallow, borne, weak, wanting, soft, sappy, spoony; dull, dull as a beetle; stupid, heavy, insulse^†, obtuse, blunt, stolid, doltish; asinine; inapt etc. 699; prosaic etc. 843; hebetudinous^†.    childish, child-like; infantine^†, infantile, babyish, babish^†; puerile, anile; simple etc. (credulous) 486; old-womanish.    fatuous, idiotic, imbecile, driveling; blatant, babbling; vacant; sottish; bewildered etc. 475.    blockish^†, unteachable Boeotian, Boeotic; bovine; ungifted, undiscerning^†, unenlightened, unwise, unphilosophical^†; apish; simious^†.    foolish, silly, senseless, irrational, insensate, nonsensical, inept; maudlin.    narrow-minded etc. 481; bigoted etc. (obstinate) 606; giddy etc. (thoughtless) 458; rash etc. 863; eccentric etc. (crazed) 503.    [Applied to actions] foolish, unwise, injudicious, improper, unreasonable, without reason, ridiculous, absurd, idiotic, silly, stupid, asinine; ill-imagined, ill-advised, ill-judged, ill-devised; mal entendu [Fr.]; inconsistent, irrational, unphilosophical^†; extravagant etc. (nonsensical) 497; sleeveless, idle; pointless, useless etc. 645; inexpedient etc. 647; frivolous etc. (trivial) 643.    ... show more

Roget 486: credulous, gullible; easily deceived etc. 545; simple, green, soft, childish, silly, stupid; easily convinced; over-credulous, over confident, over trustful; infatuated, superstitious; confiding etc. (believing) 484.    ... show more

Roget 129: infantine^†, infantile; puerile; boyish, girlish, childish, babyish, kittenish; baby; newborn, unfledged, new-fledged, callow.    in the cradle, in swaddling clothes, in long clothes, in arms, in leading strings; at the breast; in one's teens.    ... show more

Polish: dziecinny, infantylny