表达 word of mouth 直译过来是嘴里说出的话，指人与人之间传播信息时的口头传述方法，和文字传播是一组对立定义。该说法的形容词形式是加连字符的word-of-mouth 口碑的，口口相传的，多用于谈论广告、宣传和推广的商业语境中。大家在这个表达前常用介词 by，意思是消息通过口头转述的方法 by word of mouth 传播开来。
例句
These days, food rating1 apps are becoming very popular. This is why many restaurants have started to put a high value on online word-of-mouth marketing2.
现在，美食评论应用正广泛地普及开来。这就是为何不少餐厅开始很看重互联网口碑的营销推广方案。
Folk tales are passed on by word of mouth, leaving no written records of who the authors might be.
民间故事是口口相传的，不会留存表明作者身份的文字记录。
It is said that in a digital world, social media has become the new word of mouth.
据了解，在数字化的世界里，社交媒体已转变成讲述信息的新平台。