# haystack

/ˈheɪˌstæk/ (US) · /hˈeɪstæk/ (UK) · CEFR B2 · Noun

Source: https://englishreference.com/word/haystack
Updated: 2026-05-25

## Definition

a large pile of dried grass or straw. It is also used to describe a situation where it is very hard to find what you are looking for.

For teachers: a large, round pile of dried grass or straw. In a figurative sense, it refers to a large, disorganized collection of data or objects from which a specific item is difficult to locate.

## Examples

- The farmer stacked the hay into a large haystack.
- Finding a specific document in that old filing cabinet is like looking for a needle in a haystack.
- The software engineer optimized the search algorithm to ensure that even within a massive haystack of unstructured data, the relevant results would be surfaced in milliseconds.

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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.