"to bring or reduce to a pure state or a condition of purity as full as possible," 1580s of metals; c. 1590 of manners ("purify from what is coarse, low, vulgar, inelegant, etc.;" from re-, here perhaps an intensive prefix, + obsolete fine (v.) "make fine," from fine (adj.) "delicate." Compare French raffiner, Italian raffinare, Spanish refinar. General and figurative sense is recorded from 1590s; of sugar from 1610s. Intransitive sense of "become pure" is from c. 1600. Related: Refined; refining.
c. 1300, purgen, "clear of a charge or suspicion," from Anglo-French purger, Old French purgier "wash, clean; refine, purify" morally or physically (12c., Modern French purger) and directly from Latin purgare "cleanse, make clean; purify," especially in reference to the body, "free from what is superfluous; remove, clear away," but also figuratively "refute, justify, vindicate," from Old Latin purigare, from purus "pure" (see pure) + root of agere "to set in motion, drive; to do, perform" (from PIE root *ag- "to drive, draw out or forth, move").
By mid-14c. as "to cleanse (a person or soul) from sin or moral defilement; to cleanse, clear, purify" (metal, etc.), also medicinally "to cleanse the body or digestive tract by a laxative, diuretic, or emetic." The figurative sense of "make ideal or pure, rid of objectionable elements or members" is by 1580s. Related: Purged; purging. The Latin verb is also the source of Spanish purgar, Italian purgare.
c. 1200, "virtuous, pure from unlawful sexual intercourse" (as defined by the Church), from Old French chaste "morally pure" (12c.), from Latin castus "clean, pure, morally pure" (see caste).
Transferred sense of "sexually pure" is by 15c., perhaps by influence of chastity, though chaste as a noun meaning "virgin person" is recorded from early 14c. Of language, etc., "free from obscenity," 1620s. Of artistic or literary style, "severely simple, unadorned," 1753. Related: Chastely.
"to chastise, punish," c. 1600, from Latin castigatus, past participle of castigare "to correct, set right; purify; chastise, punish," from castus "pure" (see caste) + agere "to do" (from PIE root *ag- "to drive, draw out or forth, move"). The notion behind the word is "make someone pure by correction or reproof." Compare purge (v.), from purus + agere. Related: Castigated; castigating; castigator; castigatory.
If thou didst put this soure cold habit on To castigate thy pride, 'twere well. [Shakespeare, "Timon" IV.iii (1607)]
late 14c., purificacioun, "ritual purification, a cleansing of the soul from guilt or defilement," originally especially in reference to the Feast of the Purification of the Virgin Mary, from Old French purificacion, from Latin purificationem (nominative purificatio) "a purifying," noun of action from past-participle stem of purificare "to make pure" (see purify). General sense of "a freeing from dirt or defilement" is from 1590s.
late 14c., of a voice, "pure, clear;" mid-15c., of abstract things, "absolute, sheer;" from Old French mier "pure" (of gold), "entire, total, complete," and directly from Latin merus "unmixed" (of wine), "pure; bare, naked;" figuratively "true, real, genuine," according to some sources probably originally "clear, bright," from PIE *mer- "to gleam, glimmer, sparkle" (source also of Old English amerian "to purify," Old Irish emer "not clear," Sanskrit maricih "ray, beam," Greek marmarein "to gleam, glimmer"). But de Vaan writes "there is no compelling reason to derive 'pure' from 'shining,'" and compares Hittite marri "just so, gratuitously," and suggests the source is a PIE *merH-o- "remaining, pure."
The English sense of "nothing less than, in the fullest sense absolute" (mid-15c., surviving now only in vestiges such as mere folly) existed for centuries alongside the apparently opposite sense of "nothing more than" (1580s, as in a mere dream).