'Ascothoracica' originates from New Latin, ultimately built from Greek roots: 'askos' (ἄσκος) meaning 'sac' and 'thorax' (θώραξ) meaning 'breast' or 'chest', with the Latin suffix '-ica' used to form taxonomic names.

'Ascothoracica' was formed as a Latinized zoological name in modern taxonomy (19th–20th century). Earlier variant spellings and treatments in the literature include forms such as 'Ascothoracida' or references to a stem like 'Ascothorax', which through taxonomic standardization became the modern group name 'Ascothoracica'.

Initially the components described a morphological notion of a 'sac-chested' form (from the Greek roots), but over time the assembled term has come to denote the specific taxonomic group of parasitic crustaceans rather than a simple morphological description.