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• oo-
  oo-

  a combining form meaning “egg,” used in the formation of compound words.
• o'o
  o'o

  noun

  any of several species of Hawaiian birds of the extinct genus Moho, especially the extinct M. nobilis (Hawaiian o'o ), which had black plumage and two tufts of yellow plumes used to make ceremonial robes for the Hawaiian kings. The last surviving species was M. braccatus (Kauai o'o ), classified as extinct in 1987.

oo-

¹ American  

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

   oogamous.

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o'o ² American  

[oh-oh] / ˈoʊ oʊ /

Or 'ō'ō

noun

o’os plural

1. any of several species of Hawaiian birds of the extinct genus Moho, especially the extinct M. nobilis (Hawaiian o'o ), which had black plumage and two tufts of yellow plumes used to make ceremonial robes for the Hawaiian kings. The last surviving species was M. braccatus (Kauai o'o ), classified as extinct in 1987.

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oo- British  

combining form

1. egg or ovum

   oosperm

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Usage

What does oo- mean? Oo- is a combining form used like a prefix meaning “egg.” It is used in many scientific terms, especially in biology. Oo- comes from the Greek ōión, meaning “egg.” The Greek ōión helps form the word ōophóros, meaning “egg-bearing” and is the source of the combining form oophoro-, used to indicate the ovary. Distantly related to the Greek ōión is the Latin word for egg, ōvum, source of the related combining forms ov-, ovi-, and ovo-, also used to mean “egg.” The Latin ōvum is ultimately the origin of ovario-, used, like oophoro-, to mean “ovary.”What are variants of oo-?When combined with words or word elements that begin with a vowel, oo- becomes o-, as in oidium.

Other Word Forms

Noun Inflected Forms

• o’os
  plural

Etymology

Origin of oo-¹

< Greek ōio-, combining form of ōión egg ¹

Origin of o'o²

First recorded in 1885–90; from Hawaiian ʿōʿō

Example Sentences

Before they were bought out, eyewear maker Oakley sported the symbol OO and mattress maker Sealy had ZZ.

From Seattle Times • Aug. 24, 2019

OO certification, notably, doesn’t specify a particular level of privacy.

From The Verge • Jun. 18, 2019

You can tell that people actually cook from Nigella from the fact that our supermarkets now stock large bunches of flat-leaf parsley and Italian OO flour, two of her signature items.

From The Guardian • Oct. 6, 2018

OK, that’s all I knew about OO, I admit it.

From The Guardian • Oct. 8, 2014

Kirby's original bottles, OO 12 00 Monday morning, the 2nd.—After breakfast despatched three-quarters of a hundred newspapers to my old and valued friends in England.

From Journal of a Voyage across the Atlantic by Moore, George