coom

[koom] /kum/
noun, Chiefly Scot. and North England
1.
soot; coal dust; smut.
2.
dust, especially sawdust or dust from a gristmill.
3.
grease from bearings, axles, etc.
Also, coomb.
Origin
1580-90; variant of culm1
British Dictionary definitions for coom

coom

/kuːm/
noun
1.
(dialect, mainly Scot & Northern English) waste material, such as dust from coal, grease from axles, etc
Word Origin
C16 (meaning: soot): probably a variant of culm1