thorny, vexing, troublesome, contentious, problematic, touchy, knotty, prickly, perplexing, ticklish, intractable, trickiest, irksome, bothersome, complicated, pesky, daunting, dicey, controversial, weighty, arcane, problematical, stickiest, troubling, baffling, abstruse, puzzling, convoluted, unsolvable, byzantine, inconvenient, divisive, costly, irresolvable, maddening, exasperating, confusing, unresolved, bewildering, intriguing, nagging, esoteric, unpopular, inscrutable, irritating, worrisome, recalcitrant, insolvable, myriad, testy, hot potato, adept, awkward, salient, annoying, mystifying, elusive, unwelcome, messy, murky, germane, pernicious, resolvable, lingering, unwieldy, loathsome, meddlesome, perilous, glaring, difficult, burdensome, simultaneous equations, unappetizing, formidable, trivial, odious, obscure, unpalatable, delicate, pesty, peculiar, longwinded, insurmountable, crucial, cumbersome, tedious, imponderable, unsettling, rancorous, noxious, unappealing, indelicate, tangled, important, complex, equivocating, tortuous, infuriating, disenchanting, tantalizing, surmountable, tempting, trickier, embarrassing, pressing, tricky, unsolved, challenging, interesting

cranky, disagreeable, fractious, galling, ill-natured, irritable, peckish, peevish, pestering, pestiferous, pettish, petulant, plaguey, plaguy, teasing, techy, tetchy, vexatious