Wikipedia
Ishvara ( Sanskrit: ईश्वर, ) is a concept in Hinduism, with a wide range of meanings that depend on the era and the school of Hinduism. In ancient texts of Indian philosophy, depending on the context, Ishvara can mean supreme soul, ruler, king, queen or husband. In medieval era Hindu texts, depending on the school of Hinduism, Ishvara means God, Supreme Being, personal god, or special Self.
In Shaivism, Ishvara is synonymous with " Shiva", as the "Supreme lord over other Gods" in the pluralistic sense, or as an Ishta-deva in pluralistic thought. In Vaishnavism, it is synonymous with Vishnu. In traditional Bhakti movements, Ishvara is one or more deities of an individual's preference from Hinduism's polytheistic canon of deities. In modern sectarian movements such as Arya Samaj and Brahmoism, Ishvara takes the form of a monotheistic God. In Yoga school of Hinduism, it is any "personal deity" or "spiritual inspiration". In Advaita Vedanta school, Ishvara is a monistic Universal Absolute that connects and is the Oneness in everyone and everything.