Vritti
vṛttiThe "fluctuations" or "waves" of the mind, from yoga's one-line definition: the churn the whole practice works on.
Yoga is defined as the settling of the mind's fluctuations, so it is worth asking what those are. The Sutras count them:
The fluctuations are of five kinds and are hindered or unhindered.
The original Sanskrit
vṛttayaḥ pañcatayyaḥ kliṣṭākliṣṭāḥ
(These are) right knowledge, indiscrimination, verbal delusion, sleep, and memory.
The original Sanskrit
pramāṇaviparyayavikalpanidrāsmṛtayaḥ
Right knowledge, error, verbal delusion, sleep, memory. Notice that accurate thoughts are on the list too: even true thinking is still churn. The aim is not better waves but water that can go still.