# prefix

/ˈpɹifɪks/ (US) · CEFR B2 · Noun

Source: https://englishreference.com/word/prefix
Updated: 2026-05-07

## Definition

a group of letters added to the beginning of a word to change its meaning. In computing, it can also be a set of numbers or characters at the start of a string.

For teachers: an affix placed before the stem of a word to modify its meaning or create a new word. In technical contexts, refers to a sequence of characters or digits at the beginning of a data string or address.

## Examples

- The prefix 'un-' changes the meaning of 'happy' to 'unhappy'.
- When calling an international number, you must first dial the correct country prefix before the local digits.
- Linguistic analysis shows that the prefix 'pre-' originates from Latin, signifying priority in time or rank, and remains one of the most productive morphemes in modern academic English.

## Usage notes

- In grammar, it is often contrasted with 'suffix'. In computing, it frequently refers to network address segments.

---

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.