to move up and down quickly and gently, especially on the surface of water

bob up and down In the harbour, the boats bobbed gently up and down on the water. 港口里的船只在水面上轻轻地上下晃动。

to move quickly in a particular direction

bob up I dropped the bottle into the water and watched it bob up to the surface a moment later. 我把瓶子丢进海里，观察到它一会儿又浮到水面上来了。

Suddenly a head bobbed up from behind the hedge. 突然从树篱后面冒出一个头来。

She bobbed a curtsy (= bent down from the knees briefly as a sign of respect) to the Queen. 她向女王行了个屈膝礼。

a women's hairstyle with the hair cut to neck length all around the head

I've had/worn my hair in a bob for ages. 我留短发已经很长时间了。

a shilling : a British coin used in the past

That coat cost me ten bob in 1956. 那件外套是1956年买的，花了我10先令。

a quick movement up and down

bob of the head She acknowledged me with a quick bob of her head. 她迅速地向我点头示意。

small things or jobs of different types

There's a handy compartment for keys and gloves and bits and bobs.

We've done a few bits and bobs around the house since we've been here.

I need to pick up one or two bits and bobs in town.

We were just shopping for a few bits and bobs for the kitchen.

used to mean that something will happen very quickly and simply

Just tell them you're a friend of mine and, Bob's your uncle, you'll get the job. 就告诉他们你是我的一个朋友，放心好了，你会得到那份工作的。