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

A separate processor, named Loon, made progress in the R&D stage, IBM added.

From Barron's • Nov. 12, 2025

Gambetta said IBM has been able to do this with its Loon quantum processor.

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

Van Loon, who also had a spell as head of coaching at Arsenal's academy, noticed how Van Dijk nurtured his people skills by recognising who could help him.

From BBC • Apr. 23, 2025

He is the cold and scornful Loon, Who, hoping that the sun shall fail, Steeps in the silver of the moon His burnished claws, his chiseled tail.

From A Tree with a Bird in it: a symposium of contemporary american poets on being shown a pear-tree on which sat a grackle by Widdemer, Margaret