: any of a subfamily (Theclinae of the family Lycaenidae) of small butterflies usually having striped markings on the underside of the wings and thin filamentous projections from the hind wings

Examples of hairstreak in a Sentence

Recent Examples on the Web
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Overall, American mistletoe is quite a beneficial member of this area’s natural ecosystem, providing early-season flowers for bees, serving as a host plant for the state-rare great purple hairstreak butterfly, and providing food and shelter for an array of bird and mammal species. Miri Talabac, baltimoresun.com, 20 Jan. 2022 So rather than tract housing, the prairies are home to rare and unusual plants and insects, such as the Acadian hairstreak, bunchgrass skipper and dusky wing butterflies. Paul Eisenberg, chicagotribune.com, 27 Sep. 2020

Word History

First Known Use

1815, in the meaning defined above

Time Traveler
The first known use of hairstreak was in 1815

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Cite this Entry

“Hairstreak.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/hairstreak. Accessed 18 Mar. 2025.

Kids Definition

hairstreak

noun
: any of various small butterflies with hairlike tails sticking out from the hind wings

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