foci

noun

SayFOH-syUS/ˈfoʊ.kaɪ/UK/ˈfəʊ.kaɪ/

1 meaning of foci

1
noun
Plural of focus. Use this form when talking about more than one focus.
Doctors found two foci of infection in his lungs.
In math class we learned that an ellipse has two foci.
Note

foci is a form of focus

focus, noun: The main thing that people pay attention to or care about. Full entry

Forms: focusfoci pluralfocuses plural
Spelling: focus → foci: irregular plural (no -s)

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