optional

US [ˈɑpʃən(ə)l]
UK [ˈɒpʃ(ə)nəl]
  • adj.可选择的;选修的
  • n.〈美〉选修科
  • Web非强制的;可选的;可以任选的
optional
adj.
1.
可选择的;选修的that you can choose to do or have if you want to
Certain courses are compulsory; others are optional.
有些课程是必修的,其他是选修的。
This model comes with a number of optional extras(= things you can choose to have but which you will have to pay extra for) .
这一型号有一系列可供选择的附件,价格另计。

Sample Sentence

Definition:
Category:AllAll,OralOral,WrittenWritten,TitleTitle,TechnicalTechnical
Source:AllAll,DictionaryDictionary,WebWeb
Difficulty:AllAll,EasyEasy,MiddleMiddle,HardHard