英语词源字典 - 在线词源网站

add (v.)[add 词源字典]: late 14c., "to join or unite (something to something else)," from Latin addere "add to, join, attach, place upon," from ad- "to" (see ad-) + -dere comb. form meaning "to put, place," from dare "to give" (see date (n.1)). Meaning "to do sums, do addition" also is from late 14c. Related: Added; adding. To add up "make sense" is from 1942.[add etymology, add origin, 英语词源]
count (v.): mid-14c., from Old French conter "add up," but also "tell a story," from Latin computare (see compute). Related: Counted; counting. Modern French differentiates compter "to count" and conter "to tell," but they are cognates.
foot (v.): c. 1400, "to dance," also "to move or travel on foot," from foot (n.). From mid-15c. as "make a footing or foundation." To foot a bill "pay the entirety of" is attested from 1848, from the process of tallying the expenses and writing the figure at the bottom ("foot") of the sheet; foot (v.) as "add up and set the sum at the foot of" is from late 15c. (compare footnote (n.)). The Old English verb gefotian meant "to hasten up." Related: Footed; footing.
sum (v.): early 14c., "to count, count up, calculate, reckon," from Old French sommer "to count, add up," or directly from Medieval Latin summare, from summa (see sum (n.)). Meaning "briefly state the substance of" is first recorded 1620s (since c. 1700 usually with up). Related: Summed; summing.