To wander or stray from the main topic or path; to digress in speech or writing.
From Latin 'divagari' (to wander), composed of 'di-' (apart) and 'vagari' (to wander). The word entered English in the 16th-17th centuries from scholarly and literary contexts where digression was common.
Your English teacher might tell you to 'stop divagating' when you go off on tangents in an essay! The word perfectly captures the aimless wandering quality of straying from your topic, and it uses the same Latin root as 'vagrant' (a wanderer) and 'vague' (ill-defined).
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