Hindi

[hin-dee] /ˈhɪn di/
noun
1.
the most widely spoken of the modern Indic vernaculars, especially its best-known variety, Western Hindi.
2.
a literary language derived from Hindustani, used by Hindus.
Origin
1790-1800; < Hindi, Urdu, equivalent to Persian Hind, Hindu (compare Sanskrit Sindhu the river Indus; sense extended to “region of the Indus, Sind”) + -ī suffix of appurtenance; replacing Hinduee < Persian Hinduī
British Dictionary definitions for Hindi

Hindi

/ˈhɪndɪ/
noun
1.
a language or group of dialects of N central India. It belongs to the Indic branch of the Indo-European family and is closely related to Urdu See also Hindustani
2.
a formal literary dialect of this language, the official language of India, usually written in Nagari script
3.
a person whose native language is Hindi
Word Origin
C18: from Hindi hindī, from Hind India, from Old Persian Hindu the river Indus
Word Origin and History for Hindi

1825 as an adjective; 1880 as a language name, from Hind "India" (see Hindu) + -i, suffix expressing relationship.