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• EO
  EO

  executive order.
• eo-
  eo-

  a combining form meaning “early,” “primeval,” used in the formation of compound words.
• e.o.
  e.o.

  abbreviation

  ex officio.

EO

¹ American  

1. executive order.

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eo- ² American  

1. a combining form meaning “early,” “primeval,” used in the formation of compound words.

   Eocene; eohippus.

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e.o. ³ American  

abbreviation

1. ex officio.

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e.o. ¹ British  

abbreviation

1. ex officio

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eo- ² British  

combining form

1. early or primeval

   Eocene

   eohippus

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Etymology

Origin of eo-

< Greek, combining form of ēṓs ( Attic héōs ) dawn; akin to east, Aurora

Example Sentences

Larry Ottaviano, vice president of sales for surveillance-camera company PVP Advanced EO Systems, said he has never seen an increase in demand like this year.

From The Wall Street Journal • May 8, 2026

“We see the signing of this EO as a substantial step towards diminishing regulatory risk in this emerging class of therapies, enabling investor comfort,” RBC Capital Markets analyst Brian Abrahams told investors.

From MarketWatch • Apr. 20, 2026

EO: I wake up, turn on my sauna, get the cold plunge going, and then I go hit the water pot and decide whether I want to have coffee or tea.

From Los Angeles Times • Sep. 10, 2025

For example, in the case of EO, highly corrosive hydrogen fluoride vapor.

From BBC • Aug. 18, 2025

"Even super-low EO? We might be able to—" "Loss of signal, Flight."

From "The Martian" by Andy Weir