What is the literary term for he was a craven loon?

There isn't a single, specific literary term for the phrase "he was a craven loon." However, it uses several literary devices and techniques:

* Metaphor: "Craven loon" is a metaphor as it compares the person to a "loon," a bird known for its silly behavior, and "craven," meaning cowardly. This comparison creates a vivid and impactful image of the person's character.

* Adjective + Noun: The combination of "craven" and "loon" is an example of adjectival phrase. This structure is concise and powerful, emphasizing the negative traits of the person.

* Concise and direct: The sentence is simple and direct, making the statement impactful and memorable.

You could also argue that it utilizes:

* Figurative Language: The phrase uses figurative language to express the speaker's strong negative opinion of the person.

* Juxtaposition: The juxtaposition of "craven" and "loon" emphasizes the absurdity and cowardliness of the person.

Therefore, while there's no single term for the phrase, it employs various literary techniques to convey a clear and negative impression of the individual.