1. adjective
2. adverb
To an extraordinary degree.
That day he ran to school extra fast.
3. noun
a) A run scored without the ball having hit the strikers bat - a wide, bye, leg bye or no ball; in Australia referred to as a sundry
extra, extra, read all about it!<! not sure if this is for the adj or the noun
b) an extra edition of a newspaper, which is printed outside of the normal printing cycle
Wikipedia foundation.