adj. 25B6; adjective
an appalling crime : SHOCKING, horrific, horrifying, horrible, terrible, awful, dreadful, ghastly, hideous, horrendous, frightful, atrocious, abominable, abhorrent, outrageous, gruesome, grisly, monstrous, heinous, egregious.
(informal) your school work is appalling : DREADFUL, awful, terrible, frightful, atrocious, disgraceful, deplorable, hopeless, lamentable; informal rotten, crummy, pathetic, pitiful, woeful, useless, lousy, abysmal, dire; Brit. informal chronic, shocking.