Purity is being one thing and nothing else — clean, unmixed, nothing added. Spring water with nothing in it but water; a gold ring stamped with a number telling you how much of it is really gold.
In science and industry it is a measurement: 99.9% purity, the purity of a sample, testing every batch for purity. The other side of the word is moral — purity of heart, purity of motive, and in older religious writing purity means staying away from sex. Politics borrows the hard version, and a purity test is what you call it when a group demands total agreement before you belong. It nearly always takes OF: the purity of the water, the purity of her intentions. The adjective is pure and the verb is purify.
1nounpurityThe state of being clean and free of anything mixed in.~9%
“The purity of the mountain air surprised him.”
2nounchemistryThe measured degree to which a substance is free of other substances.~18%
“The lab certified a purity of 99.8%.”
3nounmoralMoral or sexual innocence.~73%
“The poem treats her purity as her only virtue.”
Shares are an estimate: a language model read 11 sentences found in the wild and placed 11 of them on a sense — a count of our sample, not a measurement of English.
Purity is pure with -ity on the end, and it reached English through Old French purete from Latin puritas. Behind the Latin stands a Proto-Indo-European root, pewH-. The word has carried one idea the whole way: this thing, and nothing else mixed into it.
Proto-Indo-European
*pewH-
Latin
puritas
Old French
purete
English, today
purity
From pure + ity, from Old French purete, from Latin puritas.
Etymology from Wiktionary, CC BY-SA