Noun

1. A swimming event in which the contestants may choose any stroke.
2. (By extension) The swimming stroke commonly referred to as the front crawl or the Australian crawl.
3. A style of wrestling in which any non-injurious holds are permitted.
4. A sports event where competitors can choose their own method of participation.
5. A form of rapping in which the emcee makes up lyrics while rapping.
   • Note: also used as an adjective and adverb in all senses

Verb

1. To improvise one's own style; to ad-lib .