read someone's lips

verb2

1. •
   To discern what someone is saying by watching the shape of the mouth rather than by hearing the sounds of the words.

   • Deaf people may be able to read people's lips, but it's not a foolproof means of communication.
2. •
   To pay close attention (often imperative).

   • Read my lips. We are not going to the park today, and that is final.