Tacit means understood or agreed upon without being spoken or written down. When something is tacit, everyone involved knows it and acts on it, even though no one has actually said it out loud.

Think about the tacit rules in your classroom: nobody had to announce that you shouldn't interrupt someone mid-sentence or that you should raise your hand before speaking. These understandings developed naturally, and everyone follows them without needing reminders. Or consider how friends develop a tacit agreement about taking turns choosing what game to play, without ever sitting down to discuss a formal system.

Tacit knowledge is information you have but would struggle to explain in words, like how you balance on a bicycle or recognize when someone is joking versus serious. You know it, but you learned it through experience rather than from reading instructions.

Something tacit operates in that silent space where people simply understand each other. A family might have a tacit understanding that everyone pitches in to clean up after dinner, even though nobody posts a chore chart or makes announcements about it. The understanding just exists, quietly shaping how everyone behaves.