The developer and the first known with the term symphonic poem was the composer <em>Franz Liszt.</em>
Explanation:
Symphonic Poems are a series of <em>thirteen orchestral works</em> that are numbered as S.95-107. The first twelve were composed in ten years, although part of the material used was previously devised.
<em>Liszt wrote prefaces for nine of his poems. </em>However, the vision he had of the symphonic poem tended to be evocative, <em>using music to create a general mood or atmosphere</em> instead of illustrating a narrative or describing something literally.
