backwash vs moving ridge

backwash and moving ridge both are nouns.

Word	Noun	Adjective	Verb	Adverb
backwash	Yes	No	No	No
moving ridge	Yes	No	No	No

As nouns, moving ridge is a hypernym of backwash; that is, moving ridge is a word with a broader meaning than backwash:

backwash: the wave that spreads behind a boat as it moves forward
moving ridge: one of a series of ridges that moves across the surface of a liquid (especially across a large body of water)

Other hypernyms of backwash include wave.

backwash (noun)	moving ridge (noun)
the wave that spreads behind a boat as it moves forward	one of a series of ridges that moves across the surface of a liquid (especially across a large body of water)
the flow of air that is driven backwards by an aircraft propeller
the consequences of an event (especially a catastrophic event)