Ghastly or sinister.
Rigid and unrelenting.
Disgusting; gross.
Dismal and gloomy, cold and forbidding.
To make grim; to give a stern or forbidding aspect to.
Dreadful; causing terror, alarm and fear; awesome
Intense; extreme in degree or extent.
Formidable, powerful.
Unpleasant; disagreeable.
Very bad; lousy.
In a terrible way; to a terrible extent; terribly; awfully.