GRIMLY
grimly
(adverb) in a grim implacable manner; “he was grimly satisfied”
Source: WordNet® 3.1
Etymology 1
Adjective
grimly (comparative grimlier, superlative grimliest)
(now, rare) Grim-looking, grim-natured.
Etymology 2
Adverb
grimly (comparative more grimly, superlative most grimly)
In a grim manner.
Synonym: grisly (obsolete)
Source: Wiktionary
Grim"ly, a.
Definition: Grim; hideous; stern. [R.]
In glided Margaret's grimly ghost, And stood at William's feet. D.
Mallet.
Grim"ly, adv.
Definition: In a grim manner; fiercely. Shak.
GRIM
Grim, a. [Compar. Grimmer (-mer); superl. Grimmest (.] Etym: [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.
Definition: Of forbidding or fear-inspiring aspect; fierce; stern; surly;
cruel; frightful; horrible.
Whose grim aspect sets every joint a-shaking. Shak
.
The ridges of grim war. Milton.
Syn.-- Fierce; ferocious; furious; horrid; horrible; frightful;
ghastly; grisly; hideous; stern; sullen; sour.
Source: Webster’s Unabridged Dictionary 1913 Edition