1. 优秀的;极好的;顶呱呱的
You use cracking to describe something you think is very good or exciting.
2. 马上开始;加紧做
If you tell someone to get cracking, you are telling them to start doing something immediately.
3. 迅速地;飞速地
If you say that someone or something is moving at a cracking pace, you mean that they are moving very quickly.
1. the act of cracking something
2. a sudden sharp noise
e.g. the crack of a whip
he heard the cracking of the ice
he can hear the snap of a twig
3. the process whereby heavy molecules of naphtha or petroleum are broken down into hydrocarbons of lower molecular weight (especially in the oil-refining process)