What does "incidental" most nearly mean?

The term "incidental" is often used to describe something that is not the main focus or purpose, but occurs alongside something that is more significant. It refers to something that is secondary or subordinate to the main event or idea. In this context, "incidental" is best aligned with the meaning of "subordinate," as it implies that while the incidental element may be present, it does not hold primary importance.

The other terms do not capture the nuanced meaning of "incidental." "Fundamental" suggests something that is essential or foundational, contrasting with the idea of something being secondary. "Secretive" refers to being covert or not open about information, which does not relate to the concept of being subordinate or ancillary. "Initiation" denotes the beginning of something and lacks the connotation of secondary relevance that "incidental" carries. Thus, the choice of "subordinate" accurately reflects the essence of what "incidental" means.