summate vs tally

summate is not a noun while tally is a noun.

Word	Noun	Adjective	Verb	Adverb
summate	No	No	Yes	No
tally	Yes	No	Yes	No

As verbs, summate and tally are synonyms defined as:

Other synonyms of summate include add, add together, add up, sum, sum up, tot, tot up, total, tote up.

summate (noun)	tally (noun)
	the act of counting; reciting numbers in ascending order
	a score in baseball made by a runner touching all four bases safely
	a bill for an amount due

summate (verb)	tally (verb)
determine the sum of	determine the sum of
form or constitute a cumulative effect	keep score, as in games
	gain points in a game
	be compatible, similar or consistent; coincide in their characteristics