Hinglish is the macaronic hybrid use of colloquial Hindi and English. Its name is a portmanteau of the words Hindi and English. In spoken contexts, it typically involves code-switching or translanguaging between these languages whereby they are freely interchanged within a sentence or between sentences.

In written contexts, Hinglish colloquially refers to Romanized Hindi—Hindustani written in Roman script (i.e., English alphabet), instead of the traditional scripts such as Devanagari or Nastaliq—often with English lexical borrowings.

The word Hinglish was first recorded in 1967. Other colloquial portmanteau words for Hindustani-influenced English include: Hindish (recorded from 1972), Hindlish (1985), Henglish (1993) and Hinlish (2013).

While the term Hinglish is based on the prefix of Hindi, it does not refer exclusively to Modern Standard Hindi, but is used in the Indian subcontinent with other Indo-Aryan languages as well, and also by "British South Asian families to enliven standard English". When Hindi–Urdu is viewed as a single spoken language called Hindustani, the portmanteaus Hinglish and Urdish may mean the same code-mixed tongue, though the latter term is commonly used in India and Pakistan to precisely refer to a mixture of English with the Urdu sociolect.

Hindustani has an approximately ten-century history. In this period, it has accommodated several linguistic influences. Contact with Sanskrit, Prakrit, Pali, Apabhraṃśa, Persian, Arabic and Turkic languages has led to historical 'mixes' or fusions, e.g., Hindustani, Rekhta. Linguistic fusions were celebrated by Bhakti poets, in approximately the 15th-17th centuries as 'khichdi boli' – or amalgamated speech.

At the turn of the 18th century, with the rising dominion of the East India Company, also called 'Company Raj' (literally, 'Company Rule'), the languages of India were brought into contact with the foreign element of English. In colonized India, English became a symbol of authority and a powerful hegemonic tool to propagate British culture, including Christianity. The political ascendancy of the British extended into social and professional roles; this meant that the legal proceedings, as well as the studies in medicine and science, were conducted in English.

This led to an interest in the promotion of English into the society of Indian natives. Educated Indians, or 'brown sahibs', wished to participate in academia and pursue professional careers. Raja Rammohan Roy, a social and education reformer, advocated that English be taught to Indians by certain British gentlemen for the benefit and instruction of the native Indians. Charles Grant, the president of the East India Company's board of control, championed the cause of English education as a 'cure for darkness' where 'darkness' was 'Hindoo ignorance'. The Charter Act was passed in 1813. This legalized missionary work by the Company, including the introduction of English education. By the beginning of the twentieth century, English had become the unifying language in the Indian struggle for independence against the British.

Meanwhile, English was on its way to becoming the first global lingua franca. By the end of the twentieth century, it had special status in seventy countries, including India. Worldwide, English began to represent modernization and internationalization, with more and more jobs requiring basic fluency in it. In India especially, the language came to acquire a social prestige, 'a class apart of education', which prompted native Indian or South Asian speakers to turn bilingual, speaking their mother tongue at home or in a local context, but English in academic or work environments.