by word of mouth—hear about smth. from another person:
- I can’t remember seeing it advertised much, so most people probably hear about it by word of mouth.
mouth words—
1. form words silently with one’s lips:
- Since the mansion was wired with microphones, Howard would mouth words silently when she wanted to have a private conversation.
2. speak in an indistinct way:
- Patients treated in the intensive care unit communicate primarily through head nods and mouthing words.