early 14c., "make illustrious, glorify, make known" (a sense now obsolete), from Old French clarifiier "clarify, make clear, explain" (12c.), from Late Latin clarificare "to glorify," literally "to make clear," from Latin clarificus "brilliant," from clarus "clear, distinct" (see clear (adj.)) + combining form of facere "to make, to do" (from PIE root *dhe- "to set, put").

Meaning "make clear, purify" (especially of liquors) is from early 15c. in English. Figurative sense of "to free from obscurity, render intelligible" is from 1823.  Intransitive sense of "grow or become clear" is from 1590s. Related: Clarified; clarifying.

1610s, "act of clearing or refining" (especially of liquid substances), from French clarification, from Late Latin clarificationem (nominative clarificatio), noun of action from past participle stem of clarificare "to make clear" (see clarify). The meaning "statement revising or expanding an earlier statement but stopping short of a correction" is attested by 1969, originally in newspapers.

*kelə-, Proto-Indo-European root meaning "to shout." Perhaps imitative.

It forms all or part of: acclaim; acclamation; Aufklarung; calendar; chiaroscuro; claim; Claire; clairvoyance; clairvoyant; clamor; Clara; claret; clarify; clarinet; clarion; clarity; class; clear; cledonism; conciliate; conciliation; council; declaim; declare; disclaim; ecclesiastic; eclair; exclaim; glair; hale (v.); halyard; intercalate; haul; keelhaul; low (v.); nomenclature; paraclete; proclaim; reclaim; reconcile.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit usakala "cock," literally "dawn-calling;" Latin calare "to announce solemnly, call out," clamare "to cry out, shout, proclaim;" Middle Irish cailech "cock;" Greek kalein "to call," kelados "noise," kledon "report, fame;" Old High German halan "to call;" Old English hlowan "to low, make a noise like a cow;" Lithuanian kalba "language."

mid-15c., "clarifying, explanatory," from Medieval Latin declaratorius, from Latin declarator, from declarare "make clear, reveal, disclose, announce," from de-, here perhaps an intensive prefix (see de-) + clarare "to clarify," from clarus "clear" (see clear (adj.)). From 1580s as "making declaration or exhibition, affirmative." Related: Declaratorily.

"one who makes a declaration," 1680s, from French déclarant, from Latin declarantem (nominative declarans), present participle of declarare  "make clear, reveal, disclose, announce," from de-, here perhaps an intensive prefix (see de-) + clarare "clarify," from clarus "clear" (see clear (adj.)). Especially in law, "one whose admission or statement is sought as evidence."

1570s, "to purify, clarify, clear from dregs or impurities," from Latin defaecatus, past participle of defaecare "cleanse from dregs, purify," from the phrase de faece "from dregs" (see de- + feces). Figurative sense "purge of extraneous matter" is from 1620s. Excretory sense "void feces from the bowels" is by 1849 in medical writing, probably from French. Related: Defecated; defecating.

1530s, "making clear or manifest, explanatory," from French déclaratif and directly from Late Latin declarativus, from past-participle stem of Latin declarare "make clear, reveal, disclose, announce," from de-, here perhaps an intensive prefix (see de-) + clarare "clarify," from clarus "clear" (see clear (adj.)).

Meaning "making declaration, exhibiting" is from 1620s. The word was used in mid-15c. as a noun meaning "an explanation." Related: Declaratively.

1570s, of accounts, "to reduce to order, to set out clearly" (a sense now obsolete), from Late Latin or Medieval Latin liquidatus, past participle of liquidare "to melt, make liquid, make clear, clarify," from Latin liquidus "fluid, liquid, moist" (see liquid (adj.)). Sense of "clear away" (a debt) first recorded 1755. The meaning "wipe out, kill" is from 1924, possibly from Russian likvidirovat, ultimately from the Latin word. Related: Liquidated; liquidating.

Middle English brightenen, from Old English *beorhtnian "make bright" (see bright (adj.) + -en (1)). The intransitive sense of "become brighter" is attested from c. 1300. The figurative meaning "dispel gloom from, cheer" is from 1590s. Related: Brightened; brightening. The simple verb bright (Old English byrhtan "be bright," geberhtan "make bright") was in Middle English, often in figurative senses "cleanse, purify; clarify, explain," but has become obsolete.

mid-14c., declaren, "explain, interpret, make clear;" late 14c., "make known by words, state explicitly, proclaim, announce," from Old French declarer "explain, elucidate," or directly from Latin declarare "make clear, reveal, disclose, announce," from de-, here perhaps an intensive prefix (see de-) + clarare "to clarify," from clarus "clear" (see clear (adj.)).

From mid-15c. as "assert, affirm." Intransitive sense "make known one's thoughts or intentions" is by 1840. Related: Declared; declaring.