word-forming element meaning "one hundred" or "one hundredth part," used in English from c. 1800, from the French metric system, from Latin centi-, combining form of centum "one hundred" (see hundred).
also gramme, metric unit of weight, 1797, from French gramme (18c.), from Late Latin gramma "small weight," from Greek gramma "small weight," a special use of the classical word meaning "a letter of the alphabet" (see -gram). Adopted into English about two years before it was established in France as a unit in the metric system by law of 19 frimaire, year VIII (1799). "There seems to be no possible objection to adopting the more convenient shorter form, except that the -me records the unimportant fact that the word came to us through French" [Fowler].
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<a href="https://www.etymonline.com/word/centigram">Etymology of centigram by etymonline</a>
Harper, D. (n.d.). Etymology of centigram. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/centigram