When an animal (humans included) is so horny and eager to mate, that they'll hump whoever comes along.

Some people think that only females experience this state, but male animals also have a reputation for being achingly randy.
"Great...! Just great! We forgot to neuter our cat, and now she's in heat! I can't stand the howling!"

"While in Frankfurt (appropriately), I once asked a German storekeeper for a 'heißer Hund'- literally 'a hot dog.' He burst out laughing, as 'heißer Hund' in German suggests a dog in heat." -Richard Lederer
by Lorelili February 05, 2006
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When a creature (most likely an amimal, but can apply to humans) is so horny, it'll hump anyhthing in sight.
Mona: OMG! Look at Jack!
Mae: What the fuck is he doing?
Jack(pulling out of the dog's ass): Ooooh, yeah! Thanks again, sparky!
Sparky: Woof!
by sexie chocolate October 05, 2004
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Synonym to horny, but with a more used for animals meaning. This can still be used to describe humans. When an animal is in heat, getting some becomes a priority, so it doesn't matter with who or what.
The stray and I were both clearly in heat so I did us both a favor by releasing my load into her. Hope I didn't get that poor thing pregnant . . .
by Pop pop sizzle February 22, 2018
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Phrase meaning either "bothered", "stressed out", or "completely blown away".
Man, I caught my gurl cheatin' wit some sucka. Dat bitch got me In Heat!!!!!
by Tommie Kemper, Logan Rains November 20, 2007
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