tell tales

noun

1. a person who heedlessly or maliciously reveals private or confidential matters; tattler; talebearer.
2. a thing serving to reveal or disclose something.
3. any of various indicating or registering devices, as a time clock.
4. Music. a gauge on an organ for indicating the air pressure.
5. an indicator showing the position of a ship’s rudder.
6. a row of strips hung over a track to warn train crew members on freight trains that a low bridge, tunnel, or the like is approaching.
7. Yachting. (on a sailboat) a feather, string, or similar device, often attached to the port and starboard shrouds and to the backstay, to indicate the relative direction of the wind.
8. Squash. a narrow piece of metal across the front wall of a court, parallel to and extending 17 inches (43.2 cm) above the base: a ball striking this is an out.

adjective

9. that reveals or betrays what is not intended to be known: a telltale blush.
10. giving notice or warning of something, as a mechanical device.

noun

1. a person who tells tales about others
2. 1. an outward indication of something concealed
   2. (as modifier)a telltale paw mark
3. any of various indicators or recording devices used to monitor a process, machine, etc
4. nautical
   1. another word for dogvane
   2. one of a pair of light vanes mounted on the main shrouds of a sailing boat to indicate the apparent direction of the wind

1540s (n.), 1590s (adj.), from tell + tale, in phrase to tell a tale “relate a false or exaggerated story” (late 13c.). Divulge secrets, as in Don’t trust him; he’s apt to tell tales. This expression was first recorded about 1350. A variant, tell tales out of school, first recorded in 1530, presumably alluded to schoolchildren gossiping but was soon broadened to revealing secret or private information. Both may be obsolescent.