Hendiadys (Greek for one through two) is a Greek and Latin figure of speech used for emphasis. Two words with similar or identical meanings are used where one would be sufficient.
For example, cum amicitia atque pace, “with peace and friendship”. Because this is redundant and therefore bad form in English, it is often translated by changing one of the nouns into an adjective. E.g., “with friendly peace” or “with peaceful friendship.”