मन या विचार का शान्त न रहकर इधर-उधर जाना।

बच्चों का ध्यान खेल से भटकता है।
भटकना

Lose clarity or turn aside especially from the main subject of attention or course of argument in writing, thinking, or speaking.

She always digresses when telling a story.
Her mind wanders.
Don't digress when you give a lecture.
digress, divagate, stray, wander