15th century, in the meaning defined at sense 1
Middle English abscisioun, borrowed from Medieval Latin abscīsiōn-, abscīsiō "cutting off, felling, amputation," going back to Latin, "aposiopesis," from abscīdere "to cut off or away, remove" + -tiōn-, -tiō, suffix of action nouns; spelling abscission (in Late and Medieval Latin as abscissiōn-, abscissiō) by construing the noun as a derivative of Latin abscindere "to tear off or away" — more at abscise, abscissa
abscission
noun