cold-blooded
Americanadjective
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designating or pertaining to animals, as fishes and reptiles, whose blood temperature ranges from the freezing point upward, in accordance with the temperature of the surrounding medium; poikilothermic.
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without emotion or feeling; dispassionate; cruel.
a cold-blooded murder.
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sensitive to cold.
adjective
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having or showing a lack of feeling or pity
a cold-blooded killing
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informal particularly sensitive to cold
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Technical term: poikilothermic. (of all animals except birds and mammals) having a body temperature that varies with that of the surroundings
Other Word Forms
- cold-bloodedly adverb
- cold-bloodedness noun
Etymology
Origin of cold-blooded
First recorded in 1585–95
Compare meaning
How does cold-blooded compare to similar and commonly confused words? Explore the most common comparisons:
Explanation
A cold-blooded animal has a body temperature that varies along with the outdoor temperature, and a cold-blooded person is someone who seems to feel no emotions. Your pet lizard may love you, but she's still cold-blooded. During a hot, sunny day, a cold-blooded animal like a snake experiences a rise in body temperature, which it can only moderate by finding a shady spot to hide. When the sun goes down at night, a snake's body temperature falls. Cold-blooded people, on the other hand, regulate their body temperature even when it's chilly outside, like other warm-blooded animals. They're cruel and unfeeling, though. This meaning comes from the old-fashioned belief that blood temperature rises with emotion.
Vocabulary lists containing cold-blooded
Idioms and Expressions, List 3
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
"Insects are cold-blooded, so they are at the mercy of external temperatures," said Northwestern's Marco Gallio, who led the study.
From Science Daily • Mar. 26, 2026
They were cold-blooded, for one thing, and probably resembled lizards.
From The Wall Street Journal • Feb. 10, 2026
He said the Croatian journalist was trying to "present me as a monster, as an inhuman, as someone who not only has no emotions, but is a cold-blooded murderer".
From BBC • Nov. 21, 2025
Need I mention that a gecko is a cold-blooded lizard?
From Salon • Oct. 17, 2025
I make a drawing of the inside of the frog, with all its curlicues and bulbs, its tiny lungs, its cold-blooded amphibian heart.
From "Cat's Eye" by Margaret Atwood
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
