from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Of or relating to poetry in which traditional material is improvised at each performance by using verbal formulas as an aid to memory.
Sorry, no etymologies found.
But yes, in this case you probably mean "epithet," or "formula" if you're hitting it from the standpoint of oral-formulaic theory, which (among other things) is about plugging in units like that while your brain composes the next line of the poem. (