The story
- Old Persian𐎱𐎠𐎼𐎿 (p-a-r-s /pārs/)
- Middle Persianpʾls (/pārs/)
- Middle Persianpʾlsyk' (/pārsīg/)
- Arabicفَارِسِيّ (fārisiyy)influ.
- Persianفارسی
- English todayFarsi
Apparently first used widely in English in the late 1960s or early 1970s. From Persian فارسی (fârsi), meaning "relating to Fars", the Arabicized form of the name of the province of Pars (Early New Persian پَارْس (pārs)) which was adopted in Iran following the Arab conquest of Persia in the 7th century. The sense for the hijra argot is from Hindi फ़ारसी (fārsī) from the same word.
Etymology from Wiktionary, CC BY-SA 4.0.