extra
extra (ĕkʹstrə) adjective
Abbr. ext., ex., X
1. More than or beyond what is usual, normal, expected, or necessary. See synonyms at superfluous.
2. Better than ordinary; superior: extra fineness.
3. Subject to an additional charge: a pizza with extra cheese.
noun
1. Something more than is usual or necessary.
2. Something, such as an accessory on a motor vehicle, for which an additional charge is made.
3. A special edition of a newspaper.
4. a. An additional or alternate worker. b. A performer hired to play a minor part, as in a crowd scene.
5. Something of exceptional quality.
adverb
To an exceptional extent or degree; unusually: extra dry.
[Probably short for extraordinary.]