Mid 16th century; earliest use found in Thomas Blundeville (fl. 1561), author and translator. From post-classical Latin adarce, adarces, variants of classical Latin adarca salty deposit or efflorescence found on reeds (Pliny) from Hellenistic Greek ἀδάρκη or ἀδάρκης from Gaulish adarca, perhaps cognate with Early Irish adarc horn (although the semantic connection is unclear), of unknown origin.