1) Angrily 2) Austerely 3) Crossly 4) Dourly 5) Gloomily 6) Harsh and un-pleasant, stern 7) In a grim implacable manner 8) In a mirthless manner 9) In a sinister way 10) Morosely 11) Resentfully 12) Seriously 13) Solemnly 14) Sourly 15) Sternly 16) Taint 17) Thoughtfully Found on https://www.crosswordclues.com/clue/grimly
Grim'ly adjective Grim; hideous; stern. [ R.] « In glided Margaret's grimly ghost, And stood at William's feet.» D. Mallet. Found on http://www.encyclo.co.uk/webster/G/58