telltale

n. 1. One who officiously communicates information of the private concerns of others; one who tells that which prudence should suppress. [ 1913 Webster ]

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. [ 1913 Webster ]

3. (Naut.) (a) A mechanical attachment to the steering wheel, which, in the absence of a tiller, shows the position of the helm. (b) 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. [ 1913 Webster ]

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. [ 1913 Webster ]

5. (Zool.) The tattler. See Tattler. [ 1913 Webster ]

6. A thing that serves to disclose something or give information; a hint or indication.

It supplies many useful links and telltales. Saintsbury. [ Webster 1913 Suppl. ]

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. [ Webster 1913 Suppl. ]

[ 1913 Webster ]