Definition of "grimly"

To hear her rant, one would have supposed, who had not seen him, that her lank-haired, grimly partner, was the prettiest youth in the county of Dublin, and that all the comely lasses in Chapelizod and the country round were sighing and setting caps at him […]

1863, Sheridan Le Fanu, The House by the Churchyard

In reality it was the most terrifying sight I had seen to date: two fried eggs decorated with ketchup, Tabasco and chopped chillis in the semblance of a pair of bloodshot eyes – I would as soon have eaten my own leg. I waved the grimly thing away.

1973, Kyril Bonfiglioli, Don't Point That Thing at Me, Penguin, published 2001, page 94

He looked round and shouted grimly, "As soon as the gate is opened, you go out there - running."

1966, James Workman, The Mad Emperor, Melbourne, Sydney: Scripts, page 63

I looked out my window / The cloud was grimly forming / Waiting for the rain I saw / The one dark cloud forming

1968, “Grimly Forming”, in Peter Vandergeler (lyrics), Conspicuous Only in Its Absence, performed by The Great Society