Imagery that can be seen in the mind's eye or can be visualized by the reader as he or she reads or listens to the 3rd through the 5th lines of Coleridge's poem Kubla Khan. There is the sacred river that flows from its source that goes through "caverns" and "down to the sunless sea." You cannot only see a picture but also watch the movement and direction of the said river.
Technical because technical language refers to the skills or terminologies that are typically best understood by people who specialize in that field or area.