- plural of focus.
foci
Americannoun
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.
The fasting mice had better blood values, less fatty liver and liver inflammation and above all: they developed less liver cancer and had fewer cancer foci in the liver.
From Science Daily ● May 7, 2024
An ellipse is the set of all points in the plane the sum of whose distances from two fixed points, called the foci, is a constant.
From Textbooks ● Dec. 21, 2021
The sun is one of the foci of the elliptical orbit.
From Textbooks ● May 6, 2020
The Sun is one of the foci of the elliptical orbit.
From Textbooks ● May 6, 2020
Ellipses have two centers, or foci; the more elongated the ellipse, the farther apart these foci are.
From "Zero: The Biography of a Dangerous Idea" by Charles Seife
![]()
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.