dead reckoning vs idea

dead reckoning and idea both are nouns.

Word	Noun	Adjective	Verb	Adverb
dead reckoning	Yes	No	No	No
idea	Yes	No	No	No

As nouns, idea is a hypernym of dead reckoning; that is, idea is a word with a broader meaning than dead reckoning:

Other hypernyms of dead reckoning include approximation, estimate, estimation.

dead reckoning (noun)	idea (noun)
navigation without the aid of celestial observations	the content of cognition; the main thing you are thinking about
an estimate based on little or no information	your intention; what you intend to do
	an approximate calculation of quantity or degree or worth
	a personal view
	(music) melodic subject of a musical composition