Actually nobody knows the origin of the word “Hindi”.The word Hindi cannot be found in any ancient Vedic-Sanaţan -Hindi scripture. The word Hindi is a later day derivative with many theories as summarized below:
1. One group of intellectuals is of the opinion that the word Hindi is derived from two different words; the first word is Himalaya, and the second word is Indu. Himalaya is the highest and largest mountainous range in the world, 5.5 miles high and 150,000 miles long which marks the northern most boundary of India. The word ‘Indu’ means an ocean, and the ocean marks the southernmost boundary of India. the first two
letters, “Hi” from Himalaya, and “ndu,” from Indu, when combined becomes “Hindi”. Those people living in the land that extends from the Himalayas to the Indian Ocean are called “Hindis”; thus the word Hindi originated indigenously.
2. Other scholars think the word “Hindi” originated from the word ‘Sindhu’. The Sa sound is either pronounced or substituted by the sound of ‘Ha’. Therefore, the word ‘Sindu’ is pronounced as ‘Hindi. Sindhu is one of the largest rivers of ancient India still flowing from the Himalayas to the ocean in the western part of India. People of one geographic area
usually have different pronunciations, different languages and different cultures from other geographic areas. At times people in certain geographic area substitute a letter that changes
pronunciation but meaning of the word remains the same. For example, in Jodhpur state of Marward - now part of Rajasthan, India, folks usually substitute ‘Ha’ sound for ‘Sa’ sound. For example, ‘Saptah, or week’ is spoken as ‘Haptah’. Similarly, ‘Sadak’ or road is spoken as ‘Hadak’. Many such examples can be given in different languages. The sound of ‘Ya’ is replaced by ‘Ja’ for instance, ‘Yash’ is called ‘Jash.’ In south India, the sound of ‘Ta’ in many words is pronounced as ‘Tha’, for example ‘Arti’ is spoken as ‘Arthi’, Shanti as Shanthi.
Similarly, ‘Sharma’ is spoken as ‘Sarma’ and so on.