impure

The word 'impure' is a direct borrowing from Latin 'impurus', formed by the negative prefix 'in-' (meaning 'not') combined with the adjective 'purus' (meaning 'clean, unmixed'). The Latin 'purus' itself is of uncertain origin, though it may be connected to the Proto-Indo-European root peu- meaning 'to purify, to cleanse'. The concept evolved from a literal sense of physical contamination—such as an alloy mixed with base metals or water muddied by dirt—to encompass abstract and moral domains. Over time, 'impure' came to describe not only adulterated substances but also thoughts, actions, or states considered morally tainted or spiritually unclean, reflecting a broad metaphorical extension of the core idea of mixture with a corrupting element.