arsenation UK /ˌɑːsɪˈneɪʃn̩/US /ˌɑɹs(ə)ˈneɪʃən/ noun1 •(old-fashioned) Conversion of a substance to, or reaction of a substance with, an arsenate (“a salt or ester of arsenic acid”).A simple process for the arsenation of phenol is described. — 1919 formsarsenations