hendiadys
A figure of speech used for emphasis, where two words joined by and are used to express a single complex idea.
Some examples of hendiadys comprise two words in the bound state; others, two words in appositional hendiadys. It would seem that certain cases of appositional hendiadys are closely related to wordpairs (see WORD-PAIRS, BREAK-UP), though which way the development proceeded is far from certain.
Where it comes from
From Medieval Latin, from Ancient Greek ἕν (hén), stem of εἷς (heîs, “one”) + διά (diá, “through”) + δύο (dúo, “two”), “one [idea] through two [words]”.
Adapted from the Wiktionary entry hendiadys (CC BY-SA 4.0).