For me, the only definitions that come to mind for the word "bob" are 1) "to move gently up and down" (usually on the surface of water) and 2) a "bob haircut." I think the only one you're likely to see on a test is the first one. Objects that float on the surface of water are described as "bobbing" when the motion of the water makes them sink and rise repeatedly. By extension, any abrupt down-and-then-up motion can be described as "bobbing." The well-known term "bobbing for apples" refers to a game where apples are placed in water, and people try to get the apples out of the water without using their hands, by biting them. (I've never actually seen anyone play this game, but apparently it was popular at some point in the past.) The word "bob" describes both the motion of the apples (they bob up and down on the water) and the motion of the people's heads (they bob down into the water to try to get an apple, and then back up again).

Hello Dinghui Well I think the most common one would be to move up and down in a short quick movement. The boat was bobbing on the river I bobbed my head in approval Really anything that goes up and down Also it can be a haircut, to get/have a bob Oh and quite informally it can be money Give us a few bob mate! Hope this helps :) There are other meanings, but I think these are the most common Kind regards, Neil

In addition to the previously mentioned examples, it's also very commonly used with money. Can you lend me a few bob? I am a little short this month.

Also what Gray said about bobbing for apples is a great example, it is still a thing here especially at Halloween. You put apples in a bucket of water and try to bite an apple, but because they are bobbing, it makes it very difficult. Also sometimes you would put a coin (some bob) in the apple so it is heavier and even more difficult! Grey and Dinghui you both need to play this game :D that's your weekend sorted 👌

The word bob is mostly use for quick movement up and down