Three Mile Island

American  

noun

1. an island in the Susquehanna River, near Middletown, Pennsylvania, SE of Harrisburg: scene of a near-disastrous accident at a nuclear plant in 1979 that raised the issue of nuclear-energy safety.

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Three Mile Island ¹ Cultural  

1. The location of an accident in 1979 in a nuclear power plant — an electrical generator powered by a nuclear reactor — in Pennsylvania. The plant underwent a partial meltdown that resulted in very little leakage of radiation into the atmosphere, panic among nearby residents, losses of billions of dollars, and intense criticism of nuclear power programs in general. (Compare Chernobyl.)

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Three Mile Island ² Cultural  

1. The location of an accident in 1979 in a nuclear power plant in Pennsylvania. The plant underwent a partial meltdown that resulted in some radiation leakage into the atmosphere, panic among nearby residents, losses of billions of dollars, and intense criticism of nuclear power programs in general.

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Compare meaning

How does three-mile-island compare to similar and commonly confused words? Explore the most common comparisons:

• Chernobyl vs. Three Mile Island

Example Sentences

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Three Mile Island

Three Mile Island in Pennsylvania — the site of the worst commercial nuclear accident in U.S. history — is slated to reopen in 2027 as part of a 20-year deal to power Microsoft data centers.

From Los Angeles Times ● Aug. 16, 2026

Crane is part of Three Mile Island, a shuttered nuclear plant in Pennsylvania.

From Barron's ● May 11, 2026

Cliff Kuang and Robert Fabricant open their book User Friendly with the cautionary tale of the Three Mile Island nuclear disaster.

From Slate ● Apr. 4, 2026

Written just a few days after the 1979 accident at the Three Mile Island nuclear power plant, the worst such accident in U.S. history to date.

From Salon ● Feb. 10, 2026

A nuclear accident that occurred at Three Mile Island in Pennsylvania in 1979 was classified after the fact as a level 5.

From "Meltdown" by Deirdre Langeland