- added to an existing or usual amount or number额外的, 分外的, 外加的：
they offered him an extra thirty-five cents an hour.
他们给他每小时另加了35美分。
1
- as submodifier to a greater extent than usual; especially非常; 特别地：
he is trying to be extra good.
他正争取成为特别优秀的人。
2
- in addition另外, 额外地：
installation will cost about £60 extra.
安装需另外收费约60英镑。
1
- an item in addition to what is usual or strictly necessary额外的东西：
I had an education with all the extras.
我受过各种各样的特殊教育。
1.1
- an item for which an additional charge is made另外收费的项目：
the price you pay includes all major charges - there are no hidden extras.
你所付的费用都是主要收费项目, 决无隐藏的额外收费项目。
1.2
- a person engaged temporarily to fill out a scene in a film or play, especially as one of a crowd临时演员（尤指群众演员）。
1.3
- Cricket a run scored other than from a hit with the bat, and credited to the batting side but not to an individual batsman【板球】（非击球所得的）附加分。
1.4
- dated a special issue of a newspaper〈旧〉（报纸的）号外。
词源
mid 17th cent. (as an adjective)： probably a shortening of EXTRAORDINARY, suggested by similar forms in French and German.