IPA: /ˈtɛlˌteɪl/
KK: /ˈtɛlˌteɪl/
A sign or piece of information that reveals something, often about a situation or condition.
The telltale signs of a storm were visible in the darkening sky.
Telltale → It is formed from "tell" (from Old English *tellan*, meaning to count or relate) and "tale" (from Old English *talu*, meaning a story or narrative). The word "telltale" refers to something that reveals or indicates something, often by telling a story or providing evidence.
Think of someone 'relating' a 'story' — that's why a telltale is something that reveals information or indicates something.
No commonly confused words.