From Sanskrit पानीय (pānīya), meaning "fit for drinking" or "drinkable," derived from the root पा (pā), "to drink." The word traveled through Prakrit and Apabhraṃśa into modern Hindi, shedding its suffix to become the everyday पानी.

पानी is the universal colloquial word for water across Hindi-speaking regions of India. The more formal/literary synonym जल (jal, from Sanskrit) appears in religious contexts, poetry, and official signage (e.g., जल संरक्षण, "water conservation"). Asking for पानी is always the natural, polite choice in everyday speech. Note that in Urdu (closely related to Hindi), the same word پانی (pānī) is used identically — a rare point of unity between the two registers.