Vidya is often translated as “knowledge” – or “Science” – sometimes “truth”; “discipline”; “rules”.
In tantric texts there is often a conflation made between Vidya as mantra, goddess, and magical power. So Vidya can be thought of simultaneously as an embodied goddess, a specific kind of power, and the mastering of that power as a result of sadhana, which gives rise to siddhi. My suggestion is that Vidya can be roughly approximately to Gnosis in the sense of being a revelation – a transformative knowing.
vidyadhara/vidyadhari – “bearer (or recipient of Wisdom (or Lore)” – also “Mountain of Wisdom” (DG White, The Alchemical Body, p329)
– One through whom mastery of Vidyas results in the ability to perform magical feats, such as flight i.e. the attainment of magical siddhis. One possessed of the knowledge of magic. These terms can refer to humans, and the semi-divine Siddhas – White uses textual sources to indicate that vidyadharas can be thought of Siddhas who, through their earthly practice, have become sky-borne beings.