damp-proof course vs damp course

damp-proof course and damp course both are nouns.

Word	Noun	Adjective	Verb	Adverb
damp-proof course	Yes	No	No	No
damp course	Yes	No	No	No

As nouns, damp-proof course and damp course are synonyms defined as:

damp-proof course and damp course: a course of some impermeable material laid in the foundation walls of building near the ground to prevent dampness from rising into the building

damp-proof course (noun)	damp course (noun)
a course of some impermeable material laid in the foundation walls of building near the ground to prevent dampness from rising into the building	a course of some impermeable material laid in the foundation walls of building near the ground to prevent dampness from rising into the building