Which literary technique involves addressing an absent person or imaginary concept?

The literary technique that involves addressing an absent person or an imaginary concept is known as apostrophe. In literature, apostrophe is a figure of speech where a speaker directly addresses someone or something that is not present in the physical realm, such as an idea, a deceased person, or even an abstract concept. This technique can create a sense of intimacy or emotional intensity by allowing the speaker to express their thoughts and feelings directly to the addressed entity, even though it cannot respond. For example, in literature, one might encounter a character speaking to the moon, expressing their feelings of longing or contemplation, thereby drawing the reader deeper into the emotional landscape of the work.

The other techniques listed are distinct in function and application. Alliteration refers to the repetition of the same initial consonant sounds in a series of words, used primarily for rhythm and musicality within poetry or prose. Metaphor is a figure of speech that makes a direct comparison between two unlike things, suggesting they are alike in a significant way, which does not involve addressing a person or concept. Personification gives human traits and qualities to non-human entities or abstract ideas, allowing these non-human elements to act with human-like characteristics, but it does not involve direct address to an absent entity.