Oo is an interjection which can express glad surprise, or a moment of pleasure. Oo doesn't carry quite the wonder of its twin sister ooh, nor the astonishment of ohh, but oo has more bounce. Sometimes an oo can be angry or pained, but mostly it is a cheery sort of exclamation.

OO spelt 00 is one name for the first year of any century - the start of the decade some call the noughties. The most recent year oo, 2ooo, was also known as mm (or sometimes MM). Make of that what you will.

As a prefix oo- denotes an egg-related word, from the Greek ωιον (oion): See ooblast*, ooblick, oocyst, oocyte, oogamy, oogenesis, oogonium, ooidal, oolite, oolith*, oology, oomycete, oomycota, oophoric, oophorectomy, oophoritis, oophyte, oorial, oosphere*, oospore, oostegite, ootheca, ootid*, ootocoid, ootype and oozoa. However the words ooch, oodles*, oof*, oofy*, oojah*, oojamaflip*, ookpik, oolly, ooloi, oom*, oompah*, oomph, oon, oones, oopack, oops, ooze and oolong have hardly anything to do with eggs.
* Not noded at time of writing.

In Scottish dialect oo can mean either we or wool.

In combination oos can be used for scaring people, like this:


A w is like a little oo that we use as a consonant; in Welsh and Cornish it can also be a vowel, so another use for multiple oos is to pronounce www:


Meanwhile the Welsh ll, as in Llwyd, is a lateral fricative, a bit like the noise Donald Duck makes, and http is of course pronounced 'ht-tp': so now you know how to pronounce the whole of http:llwww as an acronym (note that the emphasis should be on the ll, as it is in italics).

Oo - pronounced something like oh - is a common word in Somali which doesn't have a direct equivalent in English; it appears in phrases such as 'oo qura' and 'oo qudha,' which both mean 'only', and 'yaanyo shiidan oo la meceeyey', meaning ketchup.

Gritchka says: In Somali, oo also means 'and' joining two verbs (but 'and' between nouns is iyo). oo also means minus, less, before in expressions of time and money. oo kale = similar. Two adjectives after a noun are conjoined by oo: nin weyn oo dheer = a man big and tall. in yar oo = a little (of). boqol (100) and kun (1000) are followed by oo. I can't identify a general meaning for it; nor can I identify the components of that expression for 'ketchup'.

Oo is also how the Chinese , meaning black or crow, is usually spelt in the context of oolong tea, and a common Japanese pronunciation of , meaning big or grand.

Ooo is the setting for Adventure Time, which is an excellent cartoon that you should probably watch.

Finally, the best joke in the world according to Lila is:

What goes 'oooooo'?

A cow with no lips.

Etymology and examples of prefix oo-: New Oxford Dictionary of English
Scottish dialect and extra oo- words: Chambers dictionary
Somali pronunciation: ww2.saturn.stpaul.k12.mn.us/somali/alphabetvowels.html and www.fortunecity.com/bally/durrus/153/somali2.html#pronunciation
Example Somali phrases: www.fortunecity.com/bally/durrus/153/somali13.html#somtoeng and http://www.hickorytech.net/~cdn/som-eng.htm
Further info on the Somali oo: Gritchka
Unicode Chinese: www.zhongwen.com