(Vṛtti): “Whirl,” a thought wave; a psycho-mental modification. Patanjali distinguishes five types of fluctuations or conditions in which the mind can function:

  1. Pramana (valid cognition)
  2. Viparyaya (misconception)
  3. Vikalpa (imagination)
  4. Nidra (sleep)
  5. Smriti (memory)