Vasana is a Sanskrit term that refers to a past impression in the mind that influences behavior. Vasanas can be good or bad: for example, responding with love when Someone is in need or, in contrast, responding defensively because a situation triggered a negative memory. In other words, a Vasana is the habitual or automatic response to situations. They can be thought of as ingrained patterns of behavior. Vasana can also mean a desire for or Expectation of something or knowledge derived from memory. (Source: Yogapedia.)