cracking

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Thermal decomposition, sometimes with catalysis, of a complex substance, especially the breaking of petroleum molecules into shorter molecules to extract low-boiling fractions such as gasoline.
2. adj. Excellent; great: had a cracking time at the dance.
3. adv. Used as an intensive: a cracking good show.

Century Dictionary and Cyclopedia

1. n. The act of breaking; a breaking or snapping.
2. n. A more or less loud sound of breaking or snapping; a resounding noise.
3. n. A process by which a compound made up of elements of varying volatility may be analyzed and the components separated by successively raising the temperature of the mixture, so that they are distilled off successively in the order of their volatility: used specifically of petroleum compounds, which in the refining process are separated by increasing the temperature of distillation.

Wiktionary

1. n. chemistry The thermal decomposition of a substance, especially that of crude petroleum in order to produce petrol / gasoline.
2. n. The formation of cracks on a surface
3. adj. Great
4. adj. Enjoyable.
5. adv. UK Very, usually associated with praise.
6. v. present participle of crack.

GNU Webster's 1913

1. n. the act of cracking something.
2. n. (Chem.) the process of making lower molecular weight hydrocarbons from heavier hydrocarbons in petroleum, by exposure to heat and catalysts. It is used to convert heavier alkanes into gasoline, or to improve the octane number of an alkane mixture.
3. adj. informal same as groovy, sense 1.

WordNet 3.0

1. adj. very good
2. n. the act of cracking something
3. n. the process whereby heavy molecules of naphtha or petroleum are broken down into hydrocarbons of lower molecular weight (especially in the oil-refining process)
4. n. a sudden sharp noise