The word did not originate among the people it describes. When ancestors of the Romani people arrived in England during the early 16th century after migrating from northwestern India via the Byzantine Empire, British locals misidentified their origin. Assuming these dark-complexioned travelers had arrived from Egypt, English speakers shortened "Egyptian" to "Gypcian," which gradually morphed into "Gypsy."
This makes the label an exonym, a name assigned to an ethnic group by outsiders, rather than an endonym, which is the internal name an ethnic group uses for itself. In the Romani language, the root word is Rom, meaning a married man or a person of Romani descent, while Roma serves as the plural noun. The related subgroups include the Sinti, who reside primarily in Germany and Central Europe, the Romanichal in the United Kingdom, and the Kale in Finland and Spain.
Applying an external label based on geographic ignorance did more than introduce a grammatical error. It laid the foundation for systematic state persecution. By 1530, the English Crown passed the Egyptians Act, which expelled these populations under penalty of asset forfeiture and imprisonment, beginning centuries of criminalization under a label the people never chose for themselves.