dredger vs lighter

dredger and lighter both are nouns.

Word	Noun	Adjective	Verb	Adverb
dredger	Yes	No	No	No
lighter	Yes	No	Yes	No

As nouns, lighter is a hypernym of dredger; that is, lighter is a word with a broader meaning than dredger:

Other hypernyms of dredger include barge, flatboat, hoy.

dredger (noun)	lighter (noun)
a barge (or a vessel resembling a barge) that is used for dredging	a device for lighting or igniting fuel or charges or fires
	a flatbottom boat for carrying heavy loads (especially on canals)
	a substance used to ignite or kindle a fire

dredger (verb)	lighter (verb)
	transport in a flatbottom boat