As a verb crumbling
is .
As a noun crumbling
is material that has crumbled away; crumbs.
As an adjective crumbly is
easy to break into small fragments; brittle or friable.
crumbling
English
Verb
(head)
Noun
(
en noun)
Material that has crumbled away; crumbs.
* Henry James, The Aspern Papers
- Blank I call it, but it was figured over with the patches that please a painter, repaired breaches, crumblings of plaster, extrusions of brick that had turned pink with time
crumbly
English
Adjective
(er)
easy to break into small fragments; brittle or friable