drain vs culvert

drain and culvert both are nouns.

Word	Noun	Adjective	Verb	Adverb
drain	Yes	No	Yes	No
culvert	Yes	No	No	No

As nouns, culvert is a hyponym of drain; that is, culvert is a word with a more specific, narrower meaning than drain:

Other hyponyms of drain include scupper, cloaca, sewer, sewerage, soil pipe, trap.

drain (noun)	culvert (noun)
emptying something accomplished by allowing liquid to run out of it	a transverse and totally enclosed drain under a road or railway
a gradual depletion of energy or resources
a pipe through which liquid is carried away
tube inserted into a body cavity (as during surgery) to remove unwanted material

drain (verb)	culvert (verb)
empty of liquid; drain the liquid from
make weak
deplete of resources
flow off gradually