Digression
DIGRESSION, noun [Latin]
1. The act of digressing; a departure from the main subject under consideration; an excursion of speech or writing.
2. The part or passage of a discourse, argument or narration, which deviates from the main subject, tenor or design, but which may have some relation to it, or be of use to it.
3. Diviation from a regular course; as, the digression of the sun is not equal. [Little Used.]