The creation of the name of Pakistan is usually credited to activist Chaudhary Rahmat Ali in 1933. The OED states that he derived the name from Urdu پاك pāk "pure" plus the suffix -stan "place", but that he additionally explained it as an acronym formed from Punjab, Afghania, Kashmir, Sind and Baluchistan. Other sources imply that he came up with the acronym first.
Urdu pāk is related to Sanskrit पावक pāvaka "pure" and the verb punāti "to clean", from Proto-Indo-European *peuh₂- "to purify". In Latin the zero-grade adjectival form *puh₂-ro- became pūrus "pure". Puritan is probably borrowed from the related pūritās "purity".