Among the currently most popular synonyms for problem are: complication, misadventure, fly in the ointment, dispute, bother, dilemma, hassle, conundrum, irritant, facer, drag, snag, plague, headache, pickle, the rub, issue, stumbling block, matter, gremlin, trouble, muddle, hiccup, catch, hitch, glitch, predicament, difficulty, mix-up, question, mess, nuisance, worry, plight, pain, pest, job, hornets' nest, mishap, hurdle, drawback, setback, how-do-you-do, phenomenon, misfortune, catch-22, vexation, quandary, downside, obstacle, pain in the neck.