What literary term refers to a figure of speech that directly addresses an absent or imaginary person or a personified abstraction?

The term that describes a figure of speech that directly addresses an absent or imaginary person, or a personified abstraction, is apostrophe. This literary device allows writers to create a dramatic effect by speaking to someone who is not present or to an abstract concept, as if they were capable of listening or responding. For example, in John Milton's Paradise Lost, the poet invokes the muse by addressing it directly, highlighting the emotional intensity of the moment.

In contrast, metaphor involves the comparison of two unlike entities without using "like" or "as," and personification gives human qualities to non-human entities but does not specifically entail direct address. Imagery pertains to the use of descriptive language that appeals to the senses and creates visual representations in the reader's mind, rather than addressing any entity directly. Therefore, apostrophe is unique in its function of establishing a conversational tone with an absent party, making it the correct choice.