Telltale

a.	1.	Telling tales; babbling.
n.	1.	One who officiously communicates information of the private concerns of others; one who tells that which prudence should suppress.
	2.	(Mus.) A movable piece of ivory, lead, or other material, connected with the bellows of an organ, that gives notice, by its position, when the wind is exhausted.
	3.	(Naut.) A mechanical attachment to the steering wheel, which, in the absence of a tiller, shows the position of the helm.
	4.	(Mach.) A machine or contrivance for indicating or recording something, particularly for keeping a check upon employees, as factory hands, watchmen, drivers, check takers, and the like, by revealing to their employers what they have done or omitted.
	5.	(Zool.) The tattler. See Tattler.
	6.	A thing that serves to disclose something or give information; a hint or indication. It supplies many useful links and telltales. - Saintsbury.
	7.	(Railroads) An arrangement consisting of long strips, as of rope, wire, or leather, hanging from a bar over railroad tracks, in such a position as to warn freight brakemen of their approach to a low overhead bridge.

Noun	1.	telltale - someone who gossips indiscreetly Synonyms: blabbermouth, talebearer, taleteller, tattler, tattletale
Adj.	1.	telltale - disclosing unintentionally; "a telling smile"; "a telltale panel of lights"; "a telltale patch of oil on the water marked where the boat went down" Synonyms: revealing, telling

a tale-bearing animal, babbling, betrayal, betrayer, blab, blabber, blabberer, blabbering, blabbermouth, blabbing, broad hint, busybody, catchword, clack, clue, communication leak, cue, cue word, dead giveaway, delator, divulgation, divulgement, divulgence, divulging, evidence, evulgation, fink, gentle hint, gesture, giveaway, glimmer, glimmering, gossip, gossip columnist, gossiper, gossipmonger, hint, hot lead, implication, index, indication, indiscretion, informer, inkling, innuendo, insinuation, intimation, key, key word, kick, lead, leak, letting out, look, narc, newsmonger, newspaperman, nod, notion, nudge, obvious clue, peacher, prompt, quidnunc, reporter, rumormonger, scandalmonger, scent, sign, signal, snitch, snitcher, spoor, spy, squealer, stool pigeon, stoolie, suggestion, suspicion, symptom, tabby, talebearer, taleteller, tattler, tattletale, telltale sign, tip-off, tittle-tattler, trace, track, unwitting disclosure, vestige, whiff, whisper, whistle-blower, wind, wink, yenta