Final answer:
The word 'imaginarium' in these lines refers to a concept or place associated with imagination or creativity.
Step-by-step explanation:
The word 'imaginarium' in these lines refers to a concept or place associated with imagination or creativity. In the given lines, the word 'imaginarium' is used to describe the use of the mind to create shifting figures and evoke a sense of theater. It highlights the power of the imagination and the ability to create and visualize artistic expressions.