By word of mouth: hearing from another person (de ouvir alguém falar; “de boca em boca”)
The new store was a success with no advertising. People found out about it by word of mouth.
A nova loja foi sucesso sem nenhuma propaganda. As pessoas ficaram conhecendo de ouvir falar.
José Roberto A. Igreja is the author and co-author of several ELT books, including:
A BRAND-NEW ELT BOOK!
600 Phrasal Verbs (with Jonathan T. Hogan)
Fluent Business English (with Robert C. Young)
English for Job Interviews (with Robert C. Young)
Fale Inglês como um Americano (with Robert C. Young)
American Idioms! (with Joe Bailey Noble III)