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.
one of a pair of light vanes mounted on the main shrouds of a sailing boat to indicate the apparent direction of the wind
Word Origin and History for tell tales
telltale
1540s (n.), 1590s (adj.), from tell + tale, in phrase to tell a tale "relate a false or exaggerated story" (late 13c.).
Idioms and Phrases with tell tales
tell tales
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.