# hash table

CEFR C1 · Compound

Source: https://englishreference.com/word/hash-table
Updated: 2026-07-22

## Definition

a way of storing information in a computer so you can find it very quickly. It uses a special code to map a piece of data to a specific spot in a list.

For teachers: a data structure that implements an associative array, mapping keys to values via a mathematical function. It provides efficient data retrieval by calculating an index into an array of buckets or slots.

## Examples

- The programmer used a hash table to store the user data.
- By implementing a hash table, the software can look up a customer's record in constant time regardless of how many millions of entries exist.
- Efficient hash table implementations must account for potential collisions, where two distinct keys generate the same index, typically resolving them through techniques like chaining or open addressing.

## Usage notes

- Commonly used in computer science and software engineering contexts.

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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.