1. 火腿
    Ham is meat from the top of the back leg of a pig, specially treated so that it can be kept for a long period of time.

ham

    e.g. ...a huge baked ham.
           巨大的烤火腿
    e.g. ...ham sandwiches.
           火腿三明治

2. 无线电爱好者；“火腿”
    A ham is a person whose hobby consists of using special radio equipment to talk to other people with the same hobby, often people who are in other countries.

ham

    e.g. I became a ham radio operator at the age of eleven.
           我在11岁时成了一名业余无线电操作员。

3. 蹩脚演员;表演过火的演员
    A ham actor is someone who acts badly, exaggerating every emotion and gesture.

4. （常指演员故意地）表演过火，夸张做作
    If actors or actresses ham it up, they exaggerate every emotion and gesture when they are acting, often deliberately because they think that the audience will be more amused.

    e.g. Thrusting themselves into the spirit of the farce, they ham it up like mad.
           他们全力投入到这部闹剧中去，极尽搞怪之能事。