Thesaurus

abominable, abstemious, acute, aggravated, atrocious, austere, awful, bad, bare, beardown, beefed-up, big, blood-and-guts, blue, brawny, bullnecked, bullocky, chaste, cold, concentrated, consuming, corked, corky, corrective, crappy, critical, crucial, dangerous, deep, deplorable, desperate, dire, disciplinal, disciplinary, disobedient, distressing, dreadful, dry, evil, exquisite, extreme, fearful, featureless, fierce, fortified, frightful, grave, grievous, hard, hefty, homely, hopeless, horrid, icky, ill, immoderate, important, incompetent, industrial-strength, inelaborate, intemperate, intense, intensified, intensive, ironlike, keen, knock-down, knockout, lamentable, life-threatening, literal, lousy, main, mediocre, mere, mischievous, monkish, muscular, naughty, negative, no-good, nonindulgent, noticeable, overwhelming, painful, pitiful, plain, poor, powerful, pretty, profound, puritan, puritanic, puritanical, raging, reinforced, renunciant, renunciative, robust, rotten, rubber, rugged, sad, screaming, self-abnegating, self-denying, self-disciplined, self-restraining, serious, severe, simple, sinewy, smart, sorry, spartan, stark, stern, stiff, stinking, stinky, strengthened, strict, strong, swingeing, tailored, tearing, terrible, terrific, thick, tough, toughened, trigger-happy, trim, unabated, unadorned, uncool, undecorated, unelaborate, unfavorable, unfavourable, unpretentious, unrhetorical, unskilled, unspeakable, unsuitable, utmost, uttermost, vanilla, vehement, violent, virile, weapons-grade, well-knit, well-set, wicked, wild, worse, worst

severe is a ADJ.