'antimaterialistically' originates from Modern English, formed by the prefix 'anti-' and the adjective 'materialistic', where 'anti-' ultimately comes from Greek 'anti' meaning 'against' and 'materialistic' derives from Latin 'materialis' (from 'materia') meaning 'matter'.

'antimaterialistically' developed by adding the adverbial suffix '-ally' to 'antimaterialistic'. 'Materialistic' evolved from 'materialism' (French 'matérialisme' and Latin 'materialis' from 'materia'), and 'anti-' has long been used in English as a productive prefix meaning 'against'.

Initially it meant simply 'against materialism' and over time has maintained that core sense, used to describe attitudes, speech, or behavior that reject materialistic values in favor of non-material concerns.