The source allows for imagined (خيالي) and fancied (وهمي) items when discussing sensory and intellectual terms. A construction may not exist externally, yet be imaginatively assembled from elements whose shapes or qualities are perceptible.
For example, an invented bird with wings made of flame recombines familiar sensory features into a nonexistent picture. This differs from a purely abstract concept whose intelligibility is not supplied by assembling visible parts.
The distinction is between actually existing outside the mind and being representable as a sensory image. One cannot decide the technical category merely by asking whether an object currently exists in the world.