divagation

Noun

• a 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
    

• a message that departs from the main subject

Related words

• Synonyms: 
  diversion , deviation , digression , deflection , deflexion , aside , excursus , parenthesis