One who, or that which, shows or points out; as, a fare indicator in a street car. [1913 Webster]
A pressure gauge; a water gauge, as for a steam boiler; an apparatus or instrument for showing the working of a machine or moving part [1913 Webster]
The part of an instrument by which an effect is indicated, as an index or pointer. [1913 Webster]
Any bird of the genus Indicator and allied genera. See Honey guide, under Honey. [1913 Webster]
That which indicates the condition of acidity, alkalinity, or the deficiency, excess, or sufficiency of a standard reagent, by causing an appearance, disappearance, or change of color, as in titration or volumetric analysis. [1913 Webster]
" The common indicators are litmus, tropæolin, phenol phthalein, potassic permanganate, etc." [1913 Webster]

Indicator card, the figure drawn by an engine indicator, by means of which the working of the engine can be investigated and its power calculated. The Illustration shows one form of indicator card, from a steam engine, together with scales by which the pressure of the steam above or below that of the atmosphere, corresponding to any position of the engine piston in its stroke, can be measured. Called also indicator diagram. -- Indicator telegraph, a telegraph in which the signals are the deflections of a magnetic needle, as in the trans-Atlantic system.

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OXFORD DICTIONARY

indicator, n.
1 a person or thing that indicates.
2 a device indicating the condition of a machine etc.
3 a recording instrument attached to an apparatus etc.
4 a board in a railway station etc. giving current information.
5 a device (esp. a flashing light) on a vehicle to show that it is about to change direction.
6 a substance which changes colour at a given stage in a chemical reaction.
7 Physics & Med. a radioactive tracer.

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THESAURUS

indicator

Fathometer, JP, Justice, arbiter, arbitrator, badge, banner, bencher, bob, character, characteristic, control indicator, count-rate meter, critic, current indicator, density indicator, depth sounder, detonation indicator, device, differentia, display, earmark, echo sounder, fault lamp, flowmeter, galvanometer, gauge, hallmark, his honor, his lordship, his worship, humidity indicator, hygrometer, idiosyncrasy, image, index, indicant, insignia, interferometer, ionization gauge, judge, justice, keynote, lead, liquid-level indicator, load indicator, logger, magistrate, mark, measure, meter, moderator, needle, note, pH meter, peculiarity, picture, plumb, plumb bob, plumb line, plummet, pointer, potentiometer, probe, property, psychometer, pyrometer, referee, representation, representative, seal, sigil, sign, signal, signature, sound, space probe, stamp, sure sign, symptom, telltale sign, thermocouple, time-interval meter, trait, turn indicator, umpire, vibration meter, voltage indicator

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ROGET THESAURUS

indicator

Evidence

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.

Indication

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.

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