'arachnean' originates from Modern English formation based on the proper name 'Arachne' (from Ancient Greek 'Ἀράχνη'), where the name referred to a mythological weaver transformed into a spider.

'arachnean' was formed in English by combining 'Arachne' with the adjectival suffix '-ean' (as in 'Aegean'), reflecting relation to Arachne; over time the formation has been used to mean 'pertaining to spiders' rather than only 'pertaining to the mythic figure'.

Initially, references to 'Arachne' emphasized the mythological person; the derived adjective came to be used more broadly to mean 'spider-related' or 'spider-like'.