Decorum

Decorum was a principle of classical rhetoric, which defined what was appropriate to each of the main styles into which Hellenistic and Latin rhetors had divided written literature: the grand style, the middle style and the low (or plain) style. Certain types of vocabulary and diction were considered appropriate for certain stylistic levels. This principle of decorum was an influential concept even in the looser rescripts of Romanticism. Poetry, perhaps more than any other literary form, usually expressed words or phrases that were not current in ordinary conversation, characterized as poetic diction.