'armadillidium' originates from Neo-Latin/modern scientific formation, combining 'armadillo' (from Spanish 'armadillo', literally 'little armored one') with the diminutive/Greek-derived suffix '-idium'.

'armadillidium' was formed in modern taxonomic usage based on the common name 'armadillo' (Spanish) and classical diminutive elements; it became established as the genus name for certain pillbugs in zoological nomenclature in the 19th century.

Initially the root 'armadillo' meant 'little armored one' (referring to the armored mammal); in the taxonomic form 'armadillidium' the sense shifted to denote a genus of small armored isopods (pillbugs).