'arylmethylated' originates from modern chemical-English compounding: the element 'aryl' + 'methyl' with the adjectival/participial suffix '-ated'. 'Aryl' is a chemical coinage derived from 'aromatic' + the radical suffix '-yl'; 'methyl' comes from Neo-Latin 'methylum' (via French 'méthyle'), ultimately from Greek elements related to 'methy' (wine) in early chemical nomenclature; the suffix '-ate' (-> '-ated') comes from Latin '-atus' used in New Latin/chemical formation to form verbs/adjectives meaning 'to make or having'.

'arylmethylated' developed in 20th-century chemical nomenclature by compounding: 'aryl' + 'methyl' formed 'arylmethyl' (a substituent name), which with the verb-forming suffix became 'arylmethylate' and then the past/adjectival form 'arylmethylated'. Earlier related terms include 'benzylated' (for phenylmethyl substitution) used in the 19th century; the broader 'arylmethyl-' usage expanded as aromatic-substituent nomenclature standardized.

Initially the components referred separately to 'an aryl group' and 'a methyl group'; over time the compound term came to mean specifically 'bearing an arylmethyl (—CH2–Ar) substituent,' and 'arylmethylated' denotes a molecule that has undergone that substitution.