telltale

noun

1. One who divulges private information with intent to hurt others.

   “Your husband is at hand; I heare his Trumpet, / We are not tell-tales, Madam; feare you not.”

   “There were some ill-natured people —tell-tales—it seemed, in Tamai; and hence there was a deal of mystery about getting up the dance.”

   “Louis tells me that the gossip of the sailors finds its way aft, and that two of the telltales have been badly beaten by their mates.”

   “The Chinese girls who saw me yesterday are telltales. I'd better wait till dark.”

   “Try to teach your child that there's a time to intervene and a time to mind your own business. Nobody loves a telltale.”

2. An indicator, such as a warning light, that serves to warn of a hazard or problem.

   “A float telltale to be provided which shall connect with indicator on first floor by a small chain run through 1-2 inch pipe and over pulleys well guarded against the weather.”

   “For example, when trailers containing new automobiles were first piggybacked two areas of potential damage became evident: (1) diesel locomotive exhaust left a film of oil on the new autos; and (2) auto windshields could be scarred or cracked by the metal-tipped "tell-tales" which warn men atop trains of oncoming bridges or tunnels. Accordingly, automobiles aboard piggyback flats are usually coupled into the train 15 or more cars behind the locomotive; and telltales have been raised.”

   “Except for informational readout displays, each discrete and distinct telltale shall be of the color shown in column 2 of Table 2.”

   “In order to resolve the discrepancy and permit the use of telltales in informational readout displays, the agency proposed the following requirement: Telltales and gauges incorporated into informational readout displays ( a ) Shall have not less than two levels of light intensity, a higher one for day and a lower one for nighttime conditions. (b) In the case of telltales amd gauges not equipped with a variable light intensity control shall have a light intensity at the higher level […]”

3. (figuratively)Something that serves to reveal something else.

   “The telltale was the lipstick on his shirt collar.”

   “It supplies many useful links and tell-tales.”

   “In most cases the event is shielded by a large mass and only telltales arrive on earth. Such telltales include neutrinos, or even some form of radiation.”

   “It can be claimed that VC-dimension is to PAC-learning what finite telltales are to Inductive inference.”

   “Just as small pieces of rock produce telltale directional noon holes, so do large pieces of rock on snow produce telltales: but these telltales are of rather a different kind.”

4. A movable piece of ivory, lead, or other material, connected to the bellows of an organ, whose position indicates when the wind is exhausted.
5. A length of yarn or ribbon attached to a sail or shroud etc to indicate the direction of the flow of the air relative to the boat.

   “The sailmakers mistake can be an excellent way to lose a race as the telltale signals were disturbed and confusing.”

   “If you turn toward the wind, the sail becomes undertrimmed, and the inside, or windward, telltale starts to rise and flutter as the flow is disturbed.”

   “The telltale shows if wind is flowing across the sail on every point of sail except a run.”

6. A mechanical attachment to the steering wheel, which, in the absence of a tiller, shows the position of the helm.
7. A compass in the cabin of a vessel, usually placed where the captain can see it at all hours, and thus inform himself of the vessel's course.
8. A machine or contrivance for indicating or recording something, particularly for keeping a check upon employees (factory hands, watchmen, drivers, etc.) by revealing to their employers what they have done or omitted.
9. A bird, the tattler.
10. A story or fable that has a moral or message.

    “"Metamorphoses . . ." is the title of a book of telltales (or serialised fables) written by Lucius Apulei¡us, a neo-platonist priest in the second century A.D.”

    “This telltale is not like the story that you put in the hands of your children, or those narrated by mothers in their children's bedrooms in Western Europe before sleep. This is a telltale that is not welcome but is forbidden to be distributed.”

adj

1. Revealing something, especially something not intended to be known.

   “I noticed the snow was dirty, a telltale sign of recent human presence.”

   “A telltale blush crept into her cheeks as he approached.”

   “Then she noticed something the huntress's hood had hidden before: Her ears. The telltale long pointed ears of elven heritage. An elvess? Here in the Empire? Why would she be an Imperial hunter? Who is she?”