From WordNet (r) 2.0 (August 2003) [wn]:
grim
adj 1: not to be placated or appeased or moved by entreaty; "grim
determination"; "grim necessity"; "Russia's final
hour, it seemed, approached with inexorable
certainty"; "relentless persecution"; "the stern
demands of parenthood" [syn: inexorable,
relentless, stern, unappeasable, unforgiving,
unrelenting]
2: shockingly repellent; inspiring horror; "ghastly wounds";
"the grim aftermath of the bombing"; "the grim task of
burying the victims"; "a grisly murder"; "gruesome
evidence of human sacrifice"; "macabre tales of war and
plague in the Middle ages"; "macabre tortures conceived by
madmen" [syn: ghastly, grisly, gruesome, macabre]
3: harshly ironic or sinister; "black humor"; "a grim joke";
"grim laughter"; "fun ranging from slapstick clowning ...
to savage mordant wit" [syn: black, mordant]
4: causing dejection; "a blue day"; "the dark days of the war";
"a week of rainy depressing weather"; "a disconsolate
winter landscape"; "the first dismal dispiriting days of
November"; "a dark gloomy day"; "grim rainy weather" [syn:
blue, dark, depressing, disconsolate, dismal,
dispiriting, gloomy]
5: harshly uninviting or formidable in manner or appearance; "a
dour, self-sacrificing life"; "a forbidding scowl"; "a
grim man loving duty more than humanity"; "undoubtedly the
grimmest part of him was his iron claw"- J.M.Barrie [syn:
dour, forbidding]
6: characterized by hopelessness; filled with gloom; "gloomy at
the thought of what he had to face"; "gloomy predictions";
"a gloomy silence"; "took a grim view of the economy";
"the darkening mood" [syn: gloomy, darkening]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Grim \Grim\ (gr[i^]m), a. [Compar. Grimmer (-m[~e]r); superl.
Grimmest (-m[e^]st).] [AS. grim; akin to G. grimm, equiv.
to G. & D. grimmig, Dan. grim, grum, Sw. grym, Icel. grimmr,
G. gram grief, as adj., hostile; cf. Gr. ?, a crushing sound,
? to neigh.]
Of forbidding or fear-inspiring aspect; fierce; stern; surly;
cruel; frightful; horrible.
[1913 Webster]
Whose grim aspect sets every joint a-shaking. --Shak.
[1913 Webster]
The ridges of grim war. --Milton.
Syn: Syn.-- Fierce; ferocious; furious; horrid; horrible;
frightful; ghastly; grisly; hideous; stern; sullen;
sour.
[1913 Webster]