lower berth vs berth

lower berth and berth both are nouns.

Word	Noun	Adjective	Verb	Adverb
lower berth	Yes	No	No	No
berth	Yes	No	Yes	No

As nouns, berth is a hypernym of lower berth; that is, berth is a word with a broader meaning than lower berth:

Other hypernyms of lower berth include built in bed, bunk.

lower berth (noun)	berth (noun)
the lower of two berths	a job in an organization
	a bed on a ship or train; usually in tiers
	a place where a craft can be made fast

lower berth (verb)	berth (verb)
	secure in or as if in a berth or dock
	come into or dock at a wharf
	provide with a berth