Definition - What does Vasana mean?
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.
Yogapedia explains Vasana
Vasanas are obstacles to spiritual growth and happiness. They are obstacles because they are skewed by our past experiences, opinions and desires. They create restlessness in the mind and attachments to the objects of desire — be they material objects, love or success.
In order to obtain spiritual growth and eventual liberation, the yogi must free him/herself from vasanas. Yoga practices such as meditation, pranayama and mantra chanting, are tools that can help achieve this freedom.