weighty

1 having a matter of importance as its topic interrupted a weighty discussion with a silly question Synonyms grave, heavy, seriousRelated Words big, consequential, eventful, important, major, material, meaningful, momentous, portentous, significant, solid, substantialNear Antonyms frivolous, insignificant, lite, little, Mickey Mouse, minor, silly, slight, small, trivial, unimportantAntonyms light, unserious

2 having great meaning or lasting effect choosing a college is a weighty decision Synonyms big, consequential, earthshaking, earth-shattering, eventful, historic, major, material, meaningful, momentous, monumental, much, significant, substantial, tectonic, importantRelated Words decisive, fatal, fateful, strategic; earnest, grave, heavy, serious, sincere; distinctive, exceptional, impressive, outstanding, prominent, remarkable; valuable, worthwhile, worthy; distinguished, eminent, great, illustrious, noble, notable, noteworthy, outstanding, preeminent, prestigious; famous, notorious, renowned; all-important, central, critical, crucial, essential, key, pivotal, seminal, vitalNear Antonyms paltry, petty, worthless; anonymous, nameless, obscure, uncelebrated, unknownAntonyms inconsequential, inconsiderable, insignificant, little, minor, negligible, slight, small, trifling, trivial, unimportant

3 having great weight lifted the weighty sack and wondered what was in it Synonyms hefty, massive, ponderous, heavyRelated Words burdensome, leaden, lumpish; bulky, elephantine, massy, outsize (also outsized), voluminous; overweight, top-heavy; solid, substantial; ultraheavyNear Antonyms airy, ethereal, feathery, fluffy, gossamer, gossamery; flimsy, insubstantial, slight; lightweight, undersized (also undersize), underweight; ultralight, ultralightweightAntonyms light, weightless

4 not joking or playful in mood or manner the police office looked at me with a rather weighty expression Synonyms earnest, grave, humorless, no-nonsense, po-faced [British], sedate, severe, sober, sobersided, solemn, staid, uncomic, unsmiling, seriousRelated Words harsh, stern, strict; businesslike, professional; dignified, distinguished, elevated, serious-minded; gloomy, grimNear Antonyms antic, comic, comical, droll, farcical, funny, hilarious, hysterical (also hysteric), laughable, light, light-headed, ludicrous, ridiculous, riotous, risible, screaming, sidesplitting, uproarious; featherbrained, flighty, frivolous, goofy, harebrained, lighthearted, puerile, scatterbrained; absurd, asinine, balmy, brainless, cockeyed, crazy, cuckoo, daffy, daft, dotty, fatuous, foolish, half-witted, insane, jerky, kooky (also kookie), loony (also looney), lunatic, mad, nonsensical, nutty, preposterous, sappy, screwball, senseless, silly, unwise, wacky (also whacky), weak-minded, witless, zanyAntonyms facetious, flip, flippant, humorous, jesting, jocular, joking, kittenish, ludic, playful

5 having power over the minds or behavior of others one of the weightiest figures in the field of pediatric medicine Synonyms authoritative, forceful, influentialRelated Words cogent, controlling, dominating, masterful; dominant, predominant, regnant, sovereign (also sovran), supreme; eminent, important, momentousNear Antonyms helpless, impotent, powerless, weak; incapable, unable