'Anthesterion' originates from Ancient Greek, specifically the word 'Ἀνθεστήριον' (anthestērion), where 'ἄνθος' ('anthos') meant 'flower' and the suffix '-τήριον' (‑ērion) indicated a place or occasion (here, a festival/month).

'Anthesterion' passed from Ancient Greek 'Ἀνθεστήριον' into Latin scholarly usage as 'Anthesterion' and was later adopted into modern English as a classical/antiquarian term referring to the Attic month or festival period.

Initially it meant 'festival (or period) of flowers' in the context of the Greek calendar and rites; over time it remained primarily a proper name for the month (and by extension the festival period) rather than a descriptive phrase.