'astraphobia' originates from Greek via New Latin, specifically the words 'astrape' (Greek ἀστραπή) and 'phobos' (Greek φόβος), where 'astrape' meant 'lightning' and 'phobos' meant 'fear'.

'astraphobia' was formed in New Latin/modern coinage by combining the Greek root 'astrape' + the suffix '-phobia' and then adopted into English to name the fear of lightning/thunder.

Initially, it meant 'fear of lightning' and over time the usage has remained largely the same, often broadened to cover fear of both thunder and lightning.