From Zenwiki

Prajňā (Sanskrit: प्रज्ञ) is the cognate of prognosis (pro-gnosis, forward-knowing, profound insight, wisdom), though the present use of it is a little different, especially in medical use. In Buddhist use, it means the profound insight or transcendental wisdom gained in deep meditation, especially in nirvana beyond karma. In the prajñā-pāramitā (prognosis-perfection) movement/tradition, it is the penetrating insight/introspection of suññatā, śūnyatā: zero-ness, emptiness of static/solid substance, due to dynamic/interdependent/impermanent nature of things