excursus

Noun

Synonyms: digression aside divagation parenthesis

WordNet 3.0

Noun (1)

a message that departs from the main subjectSynonyms: digression aside divagation parenthesis

Webster's Dictionary (GCIDE)

Excursus \Ex*cur"sus\, n. [L., fr. excurrere, excursum. See Excurrent.] A dissertation or digression appended to a work, and containing a more extended exposition of some important point or topic. [1913 Webster]