Ishvari (Sanskrit: ईश्वरी, IAST: Īśvarī) is the Divine female counterpart of Ishvara. She is shakti and infinite strength represented in a form as an all-powerful, sovereign Goddess who reigns over all the worlds.
The description quoted below for Devi pertains also to Ishvari. She is the essence of energy - the feminine / divine mother principle - as Ishvara is the essence of awareness - the masculine / divine father principle... and all forms in creation are expressions of inseparable consciousness and energy. she is the greatest source of energy in the whole universe
Because Ishvara and Ishvari are pure essences rather than forms there are no images for them, and so the Hindu Goddesses arose - such as Durga, Kali, Saraswati, Lakshmi, Uma, and many others - from the human desire for the feminine principle to appear more relatable.
When referring to divine as female, particularly in Shaktism, the feminine Īśvarī is sometimes used.