telltale
//ˈtɛlˌteɪl//
Noun
telltaleSingular
telltalesPlural
1
A person who reveals secrets or private information about others.
Don't be a telltale—keep what I told you a secret.
2
A sign or indication that reveals something hidden or secret.
The dark circles under her eyes were a telltale of sleepless nights.
Adjective
telltaleCanonical form
1
Revealing or indicating something that is meant to be hidden or secret.
The telltale stains on his shirt revealed that he had been eating chocolate.