Telltale

Part of speech: noun (n.)

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

2. 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. A mechanical attachment to the steering wheel, which, in the absence of a tiller, shows the position of the helm.

4. 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.

5. 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.

6. The tattler. See Tattler.

Part of speech: adjective (a.)

Telling tales; babbling. "The telltale heart." Poe.