telltale

[ tel-teyl ]
/ ˈtɛlˌteɪl /

noun

adjective

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

Origin of telltale

First recorded in 1540–50; tell1 + tale

OTHER WORDS FROM telltale

tell·tale·ly, adverb

British Dictionary definitions for tell tales

telltale
/ (ˈtɛlˌteɪl) /

noun

a person who tells tales about others
  1. an outward indication of something concealed
  2. (as modifier)a telltale paw mark
any of various indicators or recording devices used to monitor a process, machine, etc
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

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.