a native or inhabitant of Hindustan or India
"The traveler met many Hindu friends during his visit to Calcutta."
A person adhering to the Hindu religion (Hinduism).
"The temple was filled with devout Hindus celebrating Diwali."
In plain English: A Hindu is someone who follows an ancient religion from India that believes many gods and focuses on karma, duty, and spiritual liberation.
"She is a Hindu who celebrates Diwali with her family every year."
Of, or relating to Hinduism, or to Hindus and their culture.
"The temple is a sacred site central to Hindu worship and community life."
In plain English: Hindu is an adjective used to describe something related to Hinduism, which is a major religion practiced by many people in India and around the world.
"Many people in India celebrate their festivals with Hindu traditions and customs."
Derived from Classical Persian هِنْدُو (hindū, "Indian, Hindu"), from Middle Persian hndwk' (Hindūg, "Indian"), from hnd (Hind, "India"), from Old Persian 𐏃𐎡𐎯𐎢 (hiⁿdu-, "India"), from Sanskrit सिन्धु (síndhu, "river, stream; Indus"), from Proto-Indo-Aryan síndʰuṣ, from Proto-Indo-Iranian síndʰuš ("river").