loon

¹ American  

[loon] / lun /

noun

1. any of several large, short-tailed, web-footed, fish-eating diving birds of the genus Gavia, of the Northern Hemisphere.

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loon ² American  

[loon] / lun /

noun

1. a crazy or simple-minded person.

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loon ¹ British  

/ luːn /

noun

1. informal a simple-minded or stupid person

2. dialect a lad

3. archaic a person of low rank or occupation (esp in the phrase lord and loon )

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loon ² British  

/ luːn /

noun

1. the US and Canadian name for diver

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Etymology

Origin of loon¹

First recorded in 1625–35; perhaps alteration of loom ³

Origin of loon²

1400–50; late Middle English lowen, perhaps < Old Norse lūinn worn, tired; later influenced by loon ¹ and loony ¹

Example Sentences

IBM unveiled its Quantum Nighthawk processor, set for delivery by year-end, and made progress on the Loon processor for fault-tolerant quantum computing.

From Barron's • Nov. 12, 2025

“Last year we de-risked the blueprint — we told you how we’re going to do the theory. Now we’ve actually shown with Loon that we can build the technology,” Gambetta said.

From MarketWatch • Nov. 12, 2025

“IBM Loon will validate a new architecture to implement and scale the components needed for practical, high-efficiency quantum error correction,” the company said in a news release.

From Barron's • Nov. 12, 2025

"Inside the club there wasn't a unanimous opinion about him and I think Virgil felt that, that the opinions of the technical people were divided," Van Loon said.

From BBC • Apr. 23, 2025

Fifty years ago the Loon continued to be so common on the Broads of Norfolk that eighteen or twenty might be counted together.

From British Birds in their Haunts by Johns, Rev. C. A.