washboard vs device

washboard and device both are nouns.

Word	Noun	Adjective	Verb	Adverb
washboard	Yes	No	No	No
device	Yes	No	No	No

As nouns, device is a hypernym of washboard; that is, device is a word with a broader meaning than washboard:

washboard (noun)	device (noun)
protective covering consisting of a broad plank along a gunwale to keep water from splashing over the side	any clever maneuver
device consisting of a corrugated surface to scrub clothes on	an instrumentality invented for a particular purpose
	an emblematic design (especially in heraldry)
	any ornamental pattern or design (as in embroidery)
	something in an artistic work designed to achieve a particular effect