estimator vs adder

estimator and adder both are nouns.

Word	Noun	Adjective	Verb	Adverb
estimator	Yes	No	No	No
adder	Yes	No	No	No

As nouns, adder is a hyponym of estimator; that is, adder is a word with a more specific, narrower meaning than estimator:

Other hyponyms of estimator include number cruncher, actuary, statistician, subtracter.

estimator (noun)	adder (noun)
an expert at calculation (or at operating calculating machines)	small terrestrial viper common in northern Eurasia
	a machine that adds numbers
	a person who adds numbers