Old English cest "box, coffer, casket," from Proto-Germanic *kista (cf. Old Norse and Old High German kista, Old Frisian, Middle Dutch, German kiste, Dutch kist), an early borrowing from Latin cista "chest, box," from Greek kiste "a box, basket," from PIE *kista "woven container." Meaning extended to "thorax" 1520s, replacing breast (n.), on the metaphor of the ribs as a box for the organs. Chest of drawers is from 1590s.
The part of the body between the neck and the abdomen, enclosed by the ribs and the breastbone; thorax.
To confess something: “I know something is troubling you; I'm sure you'll feel better if you tell me and get it off your chest.”