Nouns

(n)digression, aside, excursus, divagation, parenthesisa message that departs from the main subject
(n)diversion, deviation, digression, deflection, deflexion, divagationa turning aside (of your course or attention or concern)“a diversion from the main highway”, “a digression into irrelevant details”, “a deflection from his goal”
(n)digression, excursionwandering from the main path of a journey