pure (adj.)

mid-13c., of gold, "unalloyed;" c. 1300 "unmixed, unadulterated; homogeneous," also "total, complete, absolute; bare, mere," also "sexually pure, virgin, chaste" (late 12c. as a surname, and Old English had purlamb "lamb without a blemish"), from Old French pur "pure, simple, absolute, unalloyed," figuratively "simple, sheer, mere" (12c.), from Latin purus "clean, clear; unmixed; unadorned; chaste, undefiled."

This is conjectured to be from PIE root *peue- "to purify, cleanse" (source also of Latin putus "clear, pure;" Sanskrit pavate "purifies, cleanses," putah "pure;" Middle Irish ur "fresh, new;" Old High German fowen "to sift").

It replaced Old English hlutor. The meaning "free from moral corruption" is recorded from mid-14c. In reference to bloodlines, attested from late 15c. In music, "mathematically perfect," by 1872.

Definitions of pure

pure (adj.)
without qualification; used informally as (often pejorative) intensifiers;
pure folly
Synonyms: arrant / complete / consummate / double-dyed / everlasting / gross / perfect / sodding / stark / staring / thorough / thoroughgoing / utter / unadulterated
pure (adj.)
free of extraneous elements of any kind;
pure air and water
pure primary colors
pure gold
the violin's pure and lovely song
pure tones
pure oxygen
pure (adj.)
free from discordant qualities;
pure (adj.)
concerned with theory and data rather than practice; opposed to applied;
pure science
pure (adj.)
(used of persons or behaviors) having no faults; sinless; "I felt pure and sweet as a new baby"- Sylvia Plath;
pure as the driven snow
pure (adj.)
in a state of sexual virginity;
men have decreed that their women must be pure and virginal
pure and vestal modesty
Synonyms: vestal / virgin / virginal / virtuous
pure (adj.)
(of color) being chromatically pure; not diluted with white or grey or black;
Synonyms: saturated