guessing vs dead reckoning

guessing and dead reckoning both are nouns.

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

As nouns, guessing and dead reckoning are synonyms defined as:

guessing and dead reckoning: an estimate based on little or no information

Other synonyms of guessing include guess, guesswork, shot.

guessing (noun)	dead reckoning (noun)
an estimate based on little or no information	navigation without the aid of celestial observations
	an estimate based on little or no information