# optional

/ˈɑpʃənəɫ/ (US) · /ˈɒpʃənəl/ (UK)

Source: https://englishreference.com/word/optional
Updated: 2026-06-20

## Senses

### 1. not compulsory

adjective · CEFR B1

describes something you can choose to do or not do.

For teachers: denoting something that is left to choice rather than being required or mandatory.

- The school trip is optional, so you don't have to go if you are busy.
- While the core modules are mandatory for graduation, the advanced seminar remains optional for those seeking additional credits.

Usage: Usually placed before the noun it modifies.

### 2. an elective item

noun · CEFR B2

something that is not required, like an extra subject at school.

For teachers: an item, such as a course of study or a vehicle feature, that is not compulsory.

- Leather seats are one of the many expensive optionals available for this car.
- The curriculum includes three core sciences and a wide variety of optionals ranging from art history to computer science.

Usage: Often used in the plural when referring to car features or school subjects.

### 3. programming variable

noun · CEFR C1 · Technical

a type of data in computer code that might or might not have a value.

For teachers: a container or wrapper type that may or may not contain a meaningful value, used to handle null cases safely.

- The function returns an optional because the user might not have an email address.
- By using an Optional instead of a null pointer, the developer explicitly signals that the return value might be empty, reducing runtime errors.

Usage: Often capitalized when referring to the specific class or type in languages like Swift or Java.

Teaching tip: This is a highly specific technical term; outside of software engineering, 'optional' is almost exclusively an adjective.

## Examples

- The extra training session is optional for all staff.
- In many programming languages, the final semicolon is optional if the statement is the last one in the block.
- While the core modules are mandatory for graduation, students may select from several optional electives to tailor the degree to their specific career goals.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.