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

For a mass market in heat pumps to take off, electricity can be more expensive than gas, but not that much more expensive.

From BBC • Mar. 22, 2026

If successful, Karman could dent the market share of Trane Technologies and Schneider Electric, the leaders in heat rejection systems.

From Los Angeles Times • Jan. 22, 2026

This achievement confirms that material purity plays a decisive role in heat transfer performance and opens a path toward even more efficient heat-conducting materials.

From Science Daily • Nov. 12, 2025

Another growing use case is in data centers, where aluminum is used in heat sinks, cooling systems and the structures themselves.

From The Wall Street Journal • Oct. 10, 2025

As the flame grew in heat and height, Nathan added bigger and bigger pieces of wood.

From "Healer of the Water Monster" by Brian Young