hendiadysn.

Etymology: < post-classical Latin hendiadys (also endiadis) (12th cent.), nominative form inferred from endiadyin (also endiadin , endiadiin , endiadyn ) poetical figure by which one noun is expressed by means of two, or is divided into two (7th or 8th cent. in Latin grammarians: see note), transcription of Byzantine Greek ἓν διὰ δυοῖν ‘one by means of two’ (attested as a Greek phrase in Latin grammarians) < ancient Greek ἓν (neuter) one (see henad n.) + διὰ through (see dia- prefix¹) + δυοῖν , genitive of δύο two (see duo- comb. form).The Greek phrase is apparently not found in Greek grammarians, but is frequent in the extended version of Servius' Latin commentary on Virgil's Aeneid (perhaps 7th or 8th cent.). Editions of Servius tend to give the phrase in Greek letters but the manuscripts frequently use Roman letters. Although definitions of hendiadys usually focus on the literal interpretation of ‘one by means of two’, i.e. the use of two (or more) words to express one concept, some grammarians define it as the use of a phrase with a substantive in place of an adjective (compare sense 1). Grammarians explain that poets use this figure for metrical reasons, and often cite examples from Virgil. Frequently cited examples are pateris libamus et auro ‘let us pour a libation from bowls and from gold’ ( Georgics 2. 184), for aureis pateris ‘golden bowls’, and arma virumque ‘arms and the man’ ( Aeneid 1. 1), for armatum virum ‘an armed man’. In both cases the poet uses two nouns connected by a conjunction (compare sense 2), and in both cases one of the nouns is used in place of an adjective (compare sense 1).