hot spot

1. a country or region where dangerous or difficult political situations exist or may erupt, esp. where a war, revolution, or a belligerent attitude toward other countries exists or may develop: In the 1960s, Vietnam became a hot spot.

2. Informal. any area or place of known danger, intrigue, dissension, or instability.

3. Informal. a nightclub.

4. Photog. an area of a negative or print revealing excessive light on that part of the subject.

5. a section of forest or woods where fires frequently occur.

6. an area hotter than the surrounding surface, as on the shell of a furnace.

7. Physics. an area of abnormally high radioactivity.

8. Geol. a region of molten rock below and within the lithosphere that persists long enough to leave a record of uplift and volcanic activity at the earth's surface. Cf. plume (def. 10).

9. Genetics. a chromosome site or a section of DNA having a high frequency of mutation or recombination.

10. Vet. Pathol. a moist, raw sore on the skin of a dog or cat caused by constant licking of an irritation from an allergic reaction, tangled coat, fleas, etc.

Also, hotspot.

[1925-30, Amer.]

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Region of the Earth's upper mantle that upwells to melt through the crust to form a volcanic feature.

Most volcanoes that cannot be ascribed either to a subduction zone or to seafloor spreading at midocean ridges are attributed to hot spots. The 5% of known world volcanoes not closely related to such plate margins (see plate tectonics) are regarded as hot-spot volcanoes. Hawaiian volcanoes are the best examples of this type, occurring near the centre of the northern portion of the Pacific Plate. A chain of extinct volcanoes or volcanic islands (and seamounts), such as the Hawaiian chain, can form over millions of years where a lithospheric plate moves over a hot spot. The active volcanoes all lie at one end of the chain or ridge, and the ages of the islands or the ridge increase with their distance from those sites of volcanic activity.

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