What is the term for a single movement orchestral work that generally takes a free form and has literary or pictorial associations?

The term for a single movement orchestral work that takes a more free form and is typically associated with literary or pictorial ideas is known as a symphonic poem. This type of composition is characterized by its ability to convey a narrative or depict scenes, often inspired by poetry, literature, or visual art.

Symphonic poems emerged in the 19th century, with composers like Franz Liszt being notable figures in this genre. They differ from traditional forms like sonatas or concertos, which have more rigid structural components. Instead, a symphonic poem allows for greater expressiveness and creativity, inviting the listener to engage with the music on a deeper emotional or imaginative level.

In contrast, a sonata is usually structured for multiple movements and adheres to a specific form, like the sonata-allegro form. A concerto typically features a solo instrument alongside an orchestra and is also characterized by its multiple movements. Meanwhile, a suite consists of a series of short pieces often reflecting different dance forms or styles, rather than concentrating on a single narrative or theme. The unique qualities of the symphonic poem make it the correct answer in this context.