grimly

ilottomasti, tuimasti, synkästi puhekieltä grim Grim-looking, grim-natured.
1973, Kyril Bonfiglioli, Dont Point That Thing at Me'', Penguin (2001), page 94:

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.