An expert-
1.One who has a very deep knowledge (of a subject).
nipuṇaṃ sūkṣmajñānaṃ tena carantīti naipuṇikāh...
(Stha 9.28 Vṛ Pa 428)
2.The studies in the ninth Pūrva (canonical work of earlier lore) called Vidyānupravāda.
athavā annpravādābhidhānasya....adhyayanaviśeṣā eveti.
(Sthā 9.28 Vṛ Pa 428)