Meaning

noun a small amount (especially of a drink)

noun a young child

verb determine the sum of

originBorrowed from Scots tot, a shortened form of totum (“small child; tot”), of uncertain origin, perhaps shortened from totter (“to move in an unsteady way”), Compare tottle, also Old Norse tottr (“name of a dwarf”), Swedish tutte (“small child”), Danish tommeltot (“little child”).

Etymology from Wiktionary, CC BY-SA 3.0