Webster's Revised Unabridged Dictionary · 1913

Grum

Grum (grum) , adjective

[Compare Danish grum furious, Swedish grym, Anglo-Saxon gram, and English grim, and grumble. r35.]

1.
Morose; severe of countenance; sour; surly; glum; grim.
Nick looked sour and grum. — Arbuthnof
2.
Low; deep in the throat; guttural; rumbling; as, a grum voice.