Definition of additament in English:

additament

Pronunciation /əˈdɪtəm(ə)nt/

noun

archaic, literary
  • A thing that has been added or added on to something else; an addition.

Origin

Late Middle English; earliest use found in Lanfranc's Science of Cirurgie. From classical Latin additāmentum additional factor or amount, something added, additional element from addit-, past participial stem of addere + -āmentum.