Hindu refers to an identity associated with the philosophical, religious and cultural systems that are indigenous to the Indian subcontinent. As used in the Constitution of India, the word "Hindu" is attributed to all persons professing any Indian religion (i.e. Hinduism, Jainism, Buddhism or Sikhism). In common use today, it refers to an adherent of Hinduism. There was no word or a mention of word 'Hindu' in any of the India's ancient scripts like Vedas, Upanishads, Puranas etc. to further reference this argument.
The word Hindu is derived from Sindhu, the local name for the Indus river.
With more than a billion adherents, Hinduism is the world's third largest religion. The vast majority of Hindus, approximately 940 million, live in India. Other countries with large Hindu populations include Nepal, Bangladesh, Sri Lanka, Mauritius, Suriname, Guyana, Trinidad & Tobago, United States, Fiji, United Kingdom, Singapore, Canada and the island of Bali in Indonesia.