心口

pit of the stomach / solar plexus / words and thoughts

heart / mind / intention / center / core / CL:顆|颗[ke1],個|个[ge4]

mouth / classifier for things with mouths (people, domestic animals, cannons, wells etc) / classifier for bites or mouthfuls

lit. heart and mouth as one (idiom); to say what you think / honest and straightforward

heart and mouth at variance (idiom); keeping one's real intentions to oneself / saying one thing but meaning sth different