liver rot vs black disease

liver rot and black disease both are nouns.

Word	Noun	Adjective	Verb	Adverb
liver rot	Yes	No	No	No
black disease	Yes	No	No	No

As nouns, liver rot and black disease are synonyms defined as:

liver rot and black disease: a disease of the liver (especially in sheep and cattle) caused by liver flukes and their by-products

Other synonyms of liver rot include distomatosis, sheep rot.

liver rot (noun)	black disease (noun)
a disease of the liver (especially in sheep and cattle) caused by liver flukes and their by-products	a disease of the liver (especially in sheep and cattle) caused by liver flukes and their by-products