optional

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op‧tion‧al AC /ˈɒpʃənəl $ ˈɑːp-/ adjective
[Word Family: verb: opt, coopt; noun: option; adverb: optionally; adjective: optional]
if something is optional, you do not have to do it or use it, but you can choose to if you want to OPP compulsory:
　 ▪ three optional courses
　 ▪ The other excursions are optional.
optional extra British English:
　 ▪ Leather seats are an optional extra.
REGISTER
In everyday English, people often say that you don’t have to do something rather than say it is optional:
▪ Ties are optional. ➔ You don’t have to wear a tie.
• • •
THESAURUS
not compulsory
▪optional if something is optional, you can choose whether to do it or not :
　 ▪ You don’t have to do French – it’s optional.
　 ▪ The holiday price includes optional excursions such as an evening cruise on the lake.
　 ▪ General Studies is optional for sixth-form students.
▪voluntary done because you want to do it and not because you have to – used especially about things that you do because you think they will help other people or be useful :
　 ▪ The programme is entirely voluntary, and no one will be forced to join.
　 ▪ The charity is funded by voluntary donations.

adjective
COLLOCATIONS FROM OTHER ENTRIES
optional extras (=something that you can choose to have or not)
▪ Tinted windows and a sunroof are optional extras.
COLLOCATIONS FROM CORPUS
NOUN
extra
▪ Most of the systems offer optional extras.
▪ Theories are not optional extras in science.
▪ Cruising chutes and Windsurfers are available as optional extras on some yachts.
▪ Made to measure in glass fibre with toughened glass roof and sides, optional extras include ventilation and double glazing.
EXAMPLES FROM OTHER ENTRIES
▪ Attendance at the meeting is optional.
▪ General Studies is optional for sixth-form students.
▪ The holiday price includes entertainment in the evenings, and there are optional excursions on offer every day.
▪ You don't have to do French - it's optional.
EXAMPLES FROM CORPUS
▪ All freshmen who attend optional orientation sessions receive information on date rape.
▪ At the same time optional accessories, such as cornices, light pelmets and plinths, could also be changed.
▪ If they wish, students can do an optional dissertation, and pick up word-processing and other computer skills.