People with type O blood are universal donors.    From Wordnet, Princeton University. 

Interjection : Hear, O Israel!.    From Dictionary.com. 

O I heard, and yet hear, angry thunder; —O you sailors!.    From Wordnik.com.  [Apostroph] Reference

O will ye fancy me, O? Wilt gae and be the Leddy O 'Drum.    From Wordnik.com.  [Ballad Book] Reference

O and O² can compare their accounts of the state of the world.    From Wordnik.com.  [Relational Quantum Mechanics] Reference

XXXX symbol at 100\%; XXX, 75\%; XX, 50\%; X, 25\%; O, O\%; OO, minus 20\%.    From Wordnik.com.  [Northern Nut Growers Association Thirty-Fourth Annual Report 1943] Reference

So, either it is not in my power to do O or it is not in my power to do O².    From Wordnik.com.  [Fatalism] Reference

Suppose that when O is built, another ship O², exactly like O, is also built.    From Wordnik.com.  [Relative Identity] Reference

O wha'll bring me a moosie O? (1), Chambers PRS (1847), 183; the 1870 ed. (p. 26) has.    From Wordnik.com.  [Craw Killed the Pussy] Reference

41 45 Frederick (D) 7 / 16-22 700 LVs 3.7 O CT 7 30 47 Pulsar 9 / 19-23 500 LVs 4.4 O+.    From Wordnik.com.  [Hotline On Call] Reference

41 46 Susquehanna 8 / 11-14 700 LVs 3.7 O RI 4 31 45 RI College 9 / 17-24 742 RVs 3.6 O+.    From Wordnik.com.  [Hotline On Call] Reference

New Mexico and N e v a d a, t w O t O p O b a m a targets, recorded narrow leads for McCain.    From Wordnik.com.  [Top Stories - Google News] Reference

39 46 Hoffman (R) 9 / 8-9 600 RVs 4.0 O PA 21 40 54 StrtegicVis (R) 10 / 5-7 1200 LVs 2.8 O+.    From Wordnik.com.  [Hotline On Call] Reference

O danad O danad O danad O-- breaking off something like our Wood-pigeon's Note, which she is said to take up just where she left off.    From Wordnik.com.  [The Rubaiyat of Omar Khayyam] Reference

Then, O priests, king Yama says to him, “O man!.    From Wordnik.com.  [Death's Messengers. II. The Doctrine. 1. Translated from the Anguttara-Nikya (iii. 351).] Reference

Given two points O and O′ and a linear map φ.    From Wordnik.com.  [Citizendium, the Citizens' Compendium - Recent changes [en]] Reference

Hillary, Pres "O" is my vote in 2012, in 2016 I will bea GOP!.    From Wordnik.com.  [Clinton, Biden in 2016?] Reference

H O W L O W W I L L C O A K L E Y G O?.    From Wordnik.com.  [AroundTheCapitol.com] Reference

Sunday, he'll join O'Neal in the NBA All-Star Game.    From Wordnik.com.  [USATODAY.com - Heat star Wade-ing into special territory] Reference

"Chris played great," Raptors coach Kevin O'Neill said.    From Wordnik.com.  [USATODAY.com] Reference

Nash knows how hard it would be to walk in O'Neal's shoes.    From Wordnik.com.  [USATODAY.com - Nash edges Shaq in tight MVP vote] Reference

But several assistants are also expected to join O'Brien's staff.    From Wordnik.com.  [USATODAY.com - College Football - Navy vs. Boston College] Reference

Box wines in O, Oprah magazine and Forbes. com | Dr Vino's wine blog.    From Wordnik.com.  [Box wines in O, Oprah magazine and Forbes.com | Dr Vino's wine blog] Reference

Kevin O'Keefe on social media for lawyers at the "Get a Life" conference.    From Wordnik.com.  [Legal Tweets] Reference

He has quickness and gets right up in O'Neal's face, er, chest, er, waist.    From Wordnik.com.  [USATODAY.com - Malik's no yellow Rose] Reference

Now all this news about the GOP smackdown by My Prez O is pleasant surprise.    From Wordnik.com.  [Think Progress » Republicans dismayed by Obama’s strong performance, say it was a ‘mistake’ to let cameras roll.] Reference

Griffin's Story follows Griffin O'Conner between the ages of nine and sixteen.    From Wordnik.com.  [REVIEW: Jumper and Griffin's Story by Steven Gould] Reference

Prez O is having to put the troops where they SHOULD HAVE been IN THE FIRST PLACE!.    From Wordnik.com.  [Think Progress » REPORT: After Voting To Kill Recovery, 110 GOP Lawmakers Tout Its Success, Ask For More Money] Reference

And it doesn't matter anyway, because The Big O is a very entertaining crime novel.    From Wordnik.com.  [Archive 2007-09-16] Reference

His six-yard toss to fullback Kevin O'Connell got the Vandals (0-1) within 21-14 with.    From Wordnik.com.  [NCAA Division I College Football - Idaho vs. Boise State] Reference

Second-year player Kevin O'Connell, who threw six passes last year, is the current backup.    From Wordnik.com.  [In his 10th year with Patriots, Belichick now 'a lot friendlier'] Reference

As for Mayborn believing so fast in O'Neills little stunt, you are of course right there too.    From Wordnik.com.  [Stargate SG-1 Watchathon - 'Shades Of Grey' (S03E18)] Reference

The comments section of the N&O is a principle reason why I could never identify with conservatism.    From Wordnik.com.  [So Proud to be a North Carolinian] Reference

A 3-pointer by Marvin O'Connor put St. Joseph's ahead, 65-61, with just under five minutes to play.    From Wordnik.com.  [NCAA Men's Basketball - Massachusetts vs. St. Josephs (Pa.)] Reference