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

See Examples For:

in heat

By combining thermal conductivity measurements with neutron scattering data, the team was able to directly connect the dramatic increase in heat flow to changes in the atomic vibrations inside the crystal.

From Science Daily ● Jul. 11, 2026

These cables are made of metal, which expands in heat, causing the lines to droop.

From BBC ● Jul. 1, 2026

“We’re moving into a world where we’re going to have shelter-in-place orders in heat waves, and we won’t be able to do outdoor work like garbage collection,” he says.

From The Wall Street Journal ● Jun. 24, 2026

Sebastien Leas, a forecaster at France's weather service, likened it to a "vacuum cleaner, drawing in heat and masses of hot air rising from North Africa" and blasting it northward in a violent torrent.

From Barron's ● Jun. 23, 2026

“Well, you can’t blame ’em in heat like this.

From "Tuck Everlasting" by Natalie Babbit