Overview
This word is difficult to define and is easier to understand by what it IS NOT.
It is NOT Poetic or Lyrical.
We can say that it’s the ordinary language of society and its how we talk, but that it isn’t exact.
It is three things in one thing and they are defined below:
It is both ordinary language (as a verb)
It is a dull or ordinary style, quality, or condition (as a description)
It is a literary medium (as a subject)
And if we push it out further, we then have to include its definition as an adjective (of, relating to, or written in prose.
But if you are ever stuck, the easiest way to remember is that we have lyrics and poetry, so everything else is PROSE.
Prose is the way people talk and the way people write without the constraints of music, musical accompaniment, performance, rhythm, meter, or metric.