BM vs faecal matter

BM and faecal matter both are nouns.

Word	Noun	Adjective	Verb	Adverb
BM	Yes	No	No	No
faecal matter	Yes	No	No	No

As nouns, BM and faecal matter are synonyms defined as:

Other synonyms of BM include dejection, faeces, fecal matter, feces, ordure, stool.

BM (noun)	faecal matter (noun)
solid excretory product evacuated from the bowels	solid excretory product evacuated from the bowels