1.  Attestation of a fact or an event; testimony. [1913 Webster]
"May we with . . . the witness of a good conscience, pursue him with any further revenge?" [1913 Webster]
"If I bear witness of myself, my witness is not true." [1913 Webster]

2.  That which furnishes evidence or proof. [1913 Webster]
"Laban said to Jacob, . . . This heap be witness, and this pillar be witness." [1913 Webster]

3.  One who is cognizant; a person who beholds, or otherwise has personal knowledge of, anything; as, an eyewitness; an earwitness. Shak. [1913 Webster]
"Upon my looking round, I was witness to appearances which filled me with melancholy and regret." [1913 Webster]

4.  One who testifies in a cause, or gives evidence before a judicial tribunal; as, the witness in court agreed in all essential facts. [1913 Webster]
"This, I confess, is haste with a witness." [1913 Webster]

1.  To see or know by personal presence; to have direct cognizance of. [1913 Webster]
"This is but a faint sketch of the incalculable calamities and horrors we must expect, should we ever witness the triumphs of modern infidelity." [1913 Webster]
"General Washington did not live to witness the restoration of peace." [1913 Webster]

2.  To give testimony to; to testify to; to attest. [1913 Webster]
"Behold how many things they witness against thee." [1913 Webster]

3.  To see the execution of, as an instrument, and subscribe it for the purpose of establishing its authenticity; as, to witness a bond or a deed. [1913 Webster]

   To bear testimony; to give evidence; to testify. Chaucer. [1913 Webster]
"The men of Belial witnessed against him." [1913 Webster]
"The witnessing of the truth was then so generally attended with this event [martyrdom] that martyrdom now signifies not only to witness, but to witness to death." [1913 Webster]

witness, n. & v.
--n.
1 a person present at some event and able to give information about it (cf. EYEWITNESS).
2 a a person giving sworn testimony. b a person attesting another's signature to a document.
3 (foll. by to, of) a person or thing whose existence, condition, etc., attests or proves something (is a living witness to their generosity).
4 testimony, evidence, confirmation.
--v.
1 tr. be a witness of (an event etc.) (did you witness the accident?).
2 tr. be witness to the authenticity of (a document or signature).
3 tr. serve as evidence or an indication of.
4 intr. (foll. by against, for, to) give or serve as evidence.

Idiom:
bear witness to (or of)
1 attest the truth of.
2 state one's belief in. call to witness appeal to for confirmation etc. witness-box (US -stand) an enclosure in a lawcourt from which witnesses give evidence.

Etymology:
OE witnes (as WIT(1), -NESS)

VB  see, behold, discern, perceive, have in sight, descry, sight, make out, discover, distinguish, recognize, spy, espy, ken, get a sight of, have a sight of, catch a sight of, get a glimpse of, have a glimpse of, catch a glimpse of, command a view of, witness, contemplate, speculate, cast the eyes on, set the eyes on, be a spectator of, look on, see sights, see at a glance, look, view, eye, lift up the eyes, open one's eye, look at, look on, look upon, look over, look about one, look round, survey, scan, inspect, run the eye over, run the eye through, reconnoiter, glance round, glance on, glance over turn one's looks upon, bend one's looks upon, direct the eyes to, turn the eyes on, cast a glance, observe, watch, see with one's own eyes, watch for, peep, peer, pry, take a peep, play at bopeep, look full in the face, look hard at, look intently, strain one's eyes, fix the eyes upon, rivet the eyes upon, stare, gaze, pore over, gloat on, leer, ogle, glare, goggle, cock the eye, squint, gloat, look askance.

N  spectator, beholder, observer, looker-on, onlooker, witness, eyewitness, bystander, passer by, sightseer, rubberneck, rubbernecker, spy, sentinel.

VB  witness, behold, look on, gawk, rubber, rubberneck.

N  evidence, facts, premises, data, praecognita, grounds, indication, criterion, testimony, testification, expert testimony, attestation, deposition, examination, admission, authority, warrant, credential, diploma, voucher, certificate, doquet, docket, testamur, record, document, pi ce justificative, deed, warranty, signature, seal, exhibit, material evidence, objective evidence, witness, indicator, hostile witness, eyewitness, earwitness, material witness, state's evidence, deponent, sponsor, cojuror, oral evidence, documentary evidence, hearsay evidence, external evidence, extrinsic evidence, internal evidence, intrinsic evidence, circumstantial evidence, cumulative evidence, ex parte evidence, presumptive evidence, collateral evidence, constructive evidence, proof, evidence in chief, secondary evidence, confirmation, corroboration, support, ratification, authentication, compurgation, wager of law, comprobation, citation, reference, legal research, literature search (experiment), showing, indicative, indicatory, deducible, grounded on, founded on, based on, corroborative, confirmatory, by inference, according to, witness, a fortiori, still more, still less, raison de plus, in corroboration, of, valeat quantum, under seal, under one's hand and seal, dictum de dicto, mise en evidence, evidence, facts, premises, data, praecognita, grounds, indication, criterion, testimony, testification, expert testimony, attestation, deposition, examination, admission, authority, warrant, credential, diploma, voucher, certificate, doquet, docket, testamur, record, document, pi ce justificative, deed, warranty, signature, seal, exhibit, material evidence, objective evidence, witness, indicator, hostile witness, eyewitness, earwitness, material witness, state's evidence, deponent, sponsor, cojuror, oral evidence, documentary evidence, hearsay evidence, external evidence, extrinsic evidence, internal evidence, intrinsic evidence, circumstantial evidence, cumulative evidence, ex parte evidence, presumptive evidence, collateral evidence, constructive evidence, proof, evidence in chief, secondary evidence, confirmation, corroboration, support, ratification, authentication, compurgation, wager of law, comprobation, citation, reference, legal research, literature search (experiment), showing, indicative, indicatory, deducible, grounded on, founded on, based on, corroborative, confirmatory, by inference, according to, witness, a fortiori, still more, still less, raison de plus, in corroboration, of, valeat quantum, under seal, under one's hand and seal, dictum de dicto, mise en evidence.

VB  be evidence, evince, show, betoken, tell of, indicate, imply, involve, argue, bespeak, breathe, have weight, carry weight, tell, speak volumes, speak for itself, rest upon, depend upon, repose on, bear witness, give evidence, testify, depose, witness, vouch for, sign, seal, undersign, set one's hand and seal, sign and seal, deliver as one's act and deed, certify, attest, acknowledge, make absolute, confirm, prove (demonstrate), indorse, countersign, corroborate, support, ratify, bear out, uphold, warrant, adduce, attest, cite, quote, refer to, appeal to, call, call to witness, bring forward, bring into court, allege, plead, produce witnesses, confront witnesses, place into evidence, mark into evidence, collect evidence, bring together evidence, rake up evidence, experiment, have a case, make out a case, establish, authenticate, substantiate, verify, make good, quote chapter and verse, bring home to, bring to book.

N  indication, symbolism, symbolization, semiology, semiotics, semeiology, semeiotics, Zeitgeist, characteristic, diagnostic, lineament, feature, trait, fingerprint, voiceprint, footprint, noseprint, cloven hoof, footfall, recognition (memory), diagnostic, divining rod, detector, sign, symbol, index, indice, indicator, point, pointer, exponent, note, token, symptom, dollar sign, dollar mark, type, figure, emblem, cipher, device, representation, epigraph, motto, posy, gesture, gesticulation, pantomime, wink, glance, leer, nod, shrug, beck, touch, nudge, dactylology, dactylonomy, freemasonry, telegraphy, chirology, byplay, dumb show, cue, hint, clue, clew, key, scent, signal, signal post, rocket, blue light, watch fire, watch tower, telegraph, semaphore, flagstaff, cresset, fiery cross, calumet, heliograph, guidon, headlight, mark, scratch, line, stroke, dash, score, stripe, streak, tick, dot, point, notch, nick, print, imprint, impress, impression, keyboard symbols, printing symbols, red letter, italics, sublineation, underlining, bold font, jotting, note, annotation, reference, blaze, cedilla, guillemets, hachure, quotation marks, ", double quotes, " ", parentheses, "( )", brackets, "", braces, "", left arrow, "<", right arrow, ">", forward slash, "/", backward slash, "\", exclamation point, "!", commercial at, "@", pound sign, "#", percent sign, "%", carat, "", ampersand, "&", asterisk, "*", hyphen, "-", dash, "-", "_", em dash, "--", plus sign, "+", equals sign, "=", question mark, "?", period, ", ", semicolon, ", ", colon, ":", comma, ", ", apostrophe, "'", single quote, "'", tilde, "~", badge, criterion, countercheck, countermark, countersign, counterfoil, duplicate, tally, label, ticket, billet, letter, counter, check, chip, chop, dib, totem, tessera, card, bill, witness, voucher, stamp, cacher, trade mark, Hall mark, signature, mark, autograph, autography, attestation, hand, hand writing, sign manual, cipher, seal, sigil, signet, hand and seal, paraph, brand, superscription, indorsement, endorsement, password, watchword, catchword, security card, pass, passkey, credentials, open sesame, timbrology, mot de passe, mot du guet, pass-parole, shibboleth, title, heading, docket, address card, visiting card, carte de visite, insignia, banner, banneret, bannerol, bandrol, flag, colors, streamer, standard, eagle, labarum, oriflamb, oriflamme, figurehead, ensign, pennon, pennant, pendant, burgee, blue Peter, jack, ancient, gonfalon, union jack, banderole, old glory, quarantine flag, vexillum, yellow-flag, yellow jack, tricolor, stars and stripes, bunting, heraldry, crest, coat of arms, arms, armorial bearings, hatchment, escutcheon, scutcheon, shield, supporters, livery, uniform, cockade, epaulet, chevron, garland, love knot, favor, beacon, cairn, post, staff, flagstaff, hand, pointer, vane, cock, weathercock, guidepost, handpost, fingerpost, directing post, signpost, pillars of Hercules, pharos, bale-fire, beacon-fire, l'etoile du Nord, landmark, seamark, lighthouse, balize, polestar, loadstar, lodestar, cynosure, guide, address, direction, name, sign, signboard, warning, omen, prefigurement, trace, record, warning &c, alarm, scepter, trophy, gauge, milestone, milepost, brand, fool's cap, check, telltale, test, mileage ticket, milliary, notification, advertisement, word of command, call, bugle call, trumpet call, bell, alarum, cry, battle cry, rallying cry, angelus, reveille, sacring bell, sanctus bell, exposition &c (explanation), proof, pattern, indicating, indicative, indicatory, denotative, connotative, diacritical, representative, typical, symbolic, pantomimic, pathognomonic, symptomatic, characteristic, demonstrative, diagnostic, exponential, emblematic, armorial, individual, known by, recognizable by, indicated, pointed, marked, denotable, indelible, in token of, symbolically, in dumb show, ecce signum, ex ungue leonem, ex pede Herculem, vide ut supra, vultus ariete fortior.

adverse witness, bear witness, bear witness against, bearing false witness, character witness, expert witness, false witness, hostile witness, jehovah's witness, lay witness, material witness, witness box, witness stand