grim - adjective

• not to be placated or appeased or moved by entreaty
• shockingly repellent; inspiring horror
• harshly ironic or sinister
• harshly uninviting or formidable in manner or appearance
• filled with melancholy and despondency
• causing dejection

grim - thesaurus

black   blue   dark   depressed   dingy   disconsolate   dismal   dispirited   dour   down   downcast   downhearted   drab   drear   dreary   forbidding   ghastly   gloomy   grisly   gruesome   inexorable   low   macabre   mordant   relentless   sick   sorry   stern   unappeasable   unforgiving   unrelenting