Dire
Part of speech: adjective
Definition: Ill-boding; portentous; as, dire omens. evil in great degree; dreadful; dismal; horrible; terrible; lamentable.
Example sentence: When you put your characters in a dire situation, they often do things that surprise even you, so you have to go back and revise your original conception of who they are.
Horrendous
Part of speech: adjective
Definition: Extremely bad; awful; terrible.
Example sentence: I'm a horrendous golfer, though I do enjoy it.