Definition - What does Jhana mean?
Jhana is a Pali term that means "meditation." It is often considered synonymous with the Sanskrit term, dhyana, which is commonly used in yogic teachings, whereas jhana is more often used in Buddhism.
Jhana refers to a meditative state in which the yogi is profoundly still and in perfect concentration. Their mind is fully immersed in and absorbed by whatever object they have chosen to focus on. This is considered to be key in developing the Buddhist quality of "right concentration."
Yogapedia explains Jhana
Within Buddhism, jhana can be a series of carefully cultivated and developed states of mind. These states cumulatively lead to what is called upekkhii-sati-piirisuddhi, or "perfect mental awareness and equanimity."
This final state of jhana is said to bring an abandonment of both pleasure and stress, where the yogi feels neither sensation. Instead, they are permeated by the light of bright, pure awareness. This can only be experienced once the yogi has passed through the initial three stages of jhana where they withdraw their senses, still their thoughts and cultivate equanimity.
Some say that in order to experience one of the states of jhana, it is necessary to transcend all desire, craving and doubt. It is only when a yogi is in a wholesome state of mind that it is possible to find jhana. Others say that mastering jhana is a mark of wisdom.