1. (饮料或食物)一口之量
    A mouthful of drink or food is the amount that you put or have in your mouth.

mouthful的解释

    e.g. She gulped down a mouthful of coffee...
           她咽下一大口咖啡。
    e.g. Chew each mouthful fully before the next bite.
           将每一口充分咀嚼后，再吃下一口。

2. 冗长而拗口的词（或短语）;难读的词（或短语）
    If you describe a long word or phrase as a mouthful, you mean that it is difficult to say.

    e.g. It's called the Pan-Carib-bean Disaster Preparedness and Prevention Project, which is quite a mouthful.
           它被称为 the Pan-Caribbean Disaster Preparedness and Prevention Project（泛加勒比备灾防灾项目），名称相当冗长拗口。