excursus Meaning, Definition & Usage

  1. noun a message that departs from the main subject
    divagation; digression; aside; parenthesis.

WordNet

Ex*cur"sus noun
Etymology
L., fr. excurrere, excursum. See Excurrent.
Definitions
  1. A dissertation or digression appended to a work, and containing a more extended exposition of some important point or topic.

Webster 1913