# NOS

Source: https://englishreference.com/word/nos
Updated: 2026-08-08

## Senses

### 1. plural of no

noun · CEFR B1

more than one 'no' — for example, when many people vote against something.

For teachers: the plural form of the word 'no', typically used to count negative votes or refusals.

- The nos were much louder than the yeses during the town meeting.
- After the final tally, the nos carried the day, effectively blocking the proposed amendment to the city charter.

### 2. abbreviation for numbers

noun · CEFR B1

a short way of writing the word 'numbers'.

For teachers: a standard abbreviation for the plural noun 'numbers'.

- Please check the part nos on the list before you order them.
- The inventory sheet listed the serial nos for every piece of equipment in the laboratory to ensure accurate tracking.

### 3. nitrous oxide

noun · CEFR C1 · Informal · Slang

a gas used in car racing to make engines go much faster for a short time.

For teachers: Stands for Nitrous Oxide System. A system used in internal combustion engines to increase power output by injecting nitrous oxide.

- He hit the button for the NOS and his car zoomed past the finish line.
- The street racer installed a custom NOS kit to gain a competitive edge during the quarter-mile sprints.

### 4. new old stock

noun · CEFR C1 · Technical · Informal

old items that were never sold and are still in their original packaging.

For teachers: Stands for New Old Stock. Refers to aged inventory that has never been sold to a consumer and remains in its original, pristine condition.

- I found a NOS watch from the 1970s that has never been worn.
- Collectors often pay a significant premium for NOS components because they offer the reliability of a new part with the aesthetic of a vintage era.

### 5. not otherwise specified

adjective · CEFR C2 · Technical · Formal

Stands for Not Otherwise Specified. Used in medical or technical reports when a specific type is not named.

For teachers: Abbreviation for Not Otherwise Specified. A subcategory used in various classification systems when a condition or item does not fit into more specific categories.

- The patient was diagnosed with a mood disorder, NOS.
- The clinical report categorised the symptoms as a personality disorder NOS, pending further psychological evaluation and more specific diagnostic testing.

## Examples

- He hit the NOS button to win the race.
- Street racers often install a NOS kit to gain a competitive edge during short sprints.
- The driver waited until the final straightaway to engage the NOS, providing the necessary torque to overtake his opponent just before the finish line.

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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.