common-ground

Common ground is everything two people believe they both know — the shared floor a conversation stands on.

The term comes from Herbert Clark: mutual knowledge, mutual beliefs, mutual assumptions. Words only work where common ground exists, because a word wakes meaning rather than delivering it — and the waking only succeeds where the ground is shared. Building it is called grounding: the constant little checks ("uh-huh", a nod, a rephrase) by which speaker and listener confirm the meaning landed. (Read 2026-06-10: Grounding in communication — Wikipedia.)