'antinuclear' originates from Modern English, formed from the prefix 'anti-' (from Greek 'antí', meaning 'against') and 'nuclear' (from Latin 'nucleus', meaning 'kernel' or 'core').

'nuclear' derives from Latin 'nucleus' and Late Latin 'nuclearis'; the adjective 'nuclear' entered English, and in the 20th century the compound 'antinuclear' emerged in English usage in debates over nuclear weapons and nuclear power.

Initially the components meant 'against' and 'kernel/center', but as a compound 'antinuclear' came to mean specifically 'opposed to nuclear weapons or to nuclear power' in modern usage.