Word of mouth is news travelling person to person — someone tells a friend, the friend tells two more. No advert, no poster, no press release; just a good film someone mentioned to you at lunch.
It nearly always follows BY: you hear something by word of mouth, a restaurant fills up by word of mouth. Hyphenated, it goes in front of a noun — word-of-mouth recommendations, word-of-mouth marketing — which is what advertisers call the cheapest promotion there is. It stays singular and takes no article: say word of mouth, never a word of mouth. And it carries a quiet compliment. Something that spreads by word of mouth spread because people actually liked it enough to say so.
1nounword of mouthThe passing of news or information from one person to another in speech.
“The date was never announced; everyone heard it by word of mouth.”
2nounpersonalPersonal recommendation between customers, treated as a form of promotion.
“The shop relies on word of mouth rather than advertising.”
word of mouth is a way information spreads.
Practised in Music, Art & Culture, News & Communication, Idioms, Marketing & Advertising