Siddhidatri = Siddhi + Datri. Siddhi means 'powers' datri is 'giver and holder'. Hence Siddhidatri means the one who has all the powers and can give all kind of powers and boons to the seeker, be it human, god or anyone. Goddess manifested herself in the ninth form of divinity named Siddhidatri.
Navratri Day 9 – Siddhidatri
Gurukul Gyan Online 