in heat

Idioms  

1. In a state of sexual excitement immediately preceding ovulation. For example, Our cat's in heat so we have to keep her inside. This expression applies to most female mammals and indicates the period when the animal is fertile and most receptive to mating. [Mid-1700s]

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Example Sentences

"It is worrying, because it's ... very hard watching older people in heat, like suffering a lot," said Renata Stankeviciute, 43, a Lithuanian chef living in London.

From Barron's • May 26, 2026

Ground-level ozone, often called “smog,” is a corrosive gas that forms when pollution from vehicles and other sources reacts in heat and sunlight.

From Los Angeles Times • Apr. 22, 2026

Unlike internal combustion engines, which require a large temperature gap to operate efficiently, Stirling engines can run on much smaller differences in heat.

From Science Daily • Feb. 27, 2026

But they dropped off the pace in the second, clocking 55.04secs - the 12th-quickest time in heat two - to lose four places in the standings before Sunday's medal-deciding heats.

From BBC • Feb. 21, 2026

For her it’s blue, watercolor, not this red of mine that sucks in heat and blazes with it at the same time.

From "The Handmaid's Tale" by Margaret Atwood