开口 (kāi kǒu): To open one's mouth (verb) — Meaning & Stroke Order

A sense of unease enveloped the entire meeting room; no one dared to speak first.

After a long period of silence, he finally spoke up and revealed the truth of the matter.

I originally wanted to invite her to the exhibition this weekend, but unexpectedly hit a soft snag as soon as I opened my mouth.