patient zero
Americannoun
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Pathology. the first known carrier of infection in an outbreak.
Public health officials are tracing all contacts of infected patients, trying to work their way back to find patient zero.
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the person or thing that is believed to be the point of origin for any spreading effect, status, or event, especially if negative.
One rowdy new student was patient zero for all kinds of classroom chaos and problem behaviors.
Etymology
Origin of patient zero
First recorded in 1985–90
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.
I could not identify the patient zero of the cheese-pull phenomenon, but it was around this time that Chili’s became inescapable on TikTok—everyone stretching cheese as far as they could while praising the Triple Dipper.
From Slate • Aug. 11, 2025
Taylor Swift is patient zero for emotional contagion.
From Los Angeles Times • Jan. 4, 2024
The news reports suggested that one of them could be patient zero.
From New York Times • Jun. 21, 2023
Emile was patient zero in the worst Ebola outbreak the world has ever seen.
From Salon • Feb. 27, 2023
Doctors believe she may have been "patient zero" for the respiratory illness.
From BBC • Sep. 2, 2022
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.
