Which of the following best defines a "disloyal" person?

The term "disloyal" refers to someone who is unfaithful or treacherous, especially in a context where loyalty is expected. The word "apostate" specifically denotes a person who has abandoned or renounced their religious or political beliefs. This abandonment can extend to a broader sense of betrayal or disloyalty, making "apostate" a fitting choice for describing someone who is disloyal, particularly in contexts related to faith or allegiance.

The other options convey different meanings that do not align with the concept of disloyalty. "Anodyne" pertains to something that soothes or relieves pain but does not relate to disloyalty. "Artless" refers to someone who is innocent, naïve, or lacking in guile, which contradicts the idea of being disloyal. "Apposite" means relevant or appropriate, again not connecting to the notion of loyalty or disloyalty. Hence, "apostate" is the term that best encapsulates the essence of being disloyal.