Vṛtti, “turning”, is a wave in the field of the mind. The Yoga Sūtras define yoga as the stilling of these movements and list five kinds: right knowledge, error, imagination, sleep and memory. When they cease, the seer abides in its own nature. In Vedānta, the mental modification shaped as Brahman removes ignorance.
Vṛtti
A movement or modification of the mind: thought, perception, memory, imagination or sleep.
Also: Vritti