weighty

Synonyms: burdensome cumbersome cumbrous dense fat fleshy hefty massive obese overweight ponderous porcine portly stout

Antonyms: light small thin unsubstantial

Synonyms: big big deal consequential considerable critical crucial earnest forcible grave heavy heavyweight life and death material meaningful momentous no-nonsense portentous sedate severe significant sober solemn somber staid substantial underlined

Antonyms: inconsequential trivial unimportant unsubstantial

Synonyms: backbreaking burdensome crushing demanding exacting exigent grievous onerous oppressive superincumbent taxing tough worrisome worrying

Antonyms: easy facile solvable