O

¹ American  

[oh] / oʊ /

Or o

noun

plural

O's, Os, o's, os, oes

1. the fifteenth letter of the English alphabet, a vowel.

2. any spoken sound represented by the letter O or o, as in box, note, short, or love .

3. something having the shape of an O .

4. a written or printed representation of the letter O or o.

5. a device, as a printer's type, for reproducing the letter O or o.

---

o- ² American  

Chemistry.

1. an abridgment of ortho-.

---

o. ³ American  

abbreviation

1. pint.

---

O. ⁴ American  

abbreviation

1. (in prescriptions) a pint.

---

O ⁵ American  

[oh] / oʊ /

interjection

1. (used before a name in direct address, especially in solemn or poetic language, to lend earnestness to an appeal).

   Hear, O Israel!

2. (used as an expression of surprise, pain, annoyance, longing, gladness, etc.)

---

noun

plural

O's

1. the exclamation “O.”

o- ⁶ American  

1. variant of ob- before m:

   omission.

---

o. ⁷ American  

abbreviation

1. octavo.

2. off.

3. old.

4. only.

5. order.

6. Baseball. out; outs.

---

O. ⁸ American  

abbreviation

1. Ocean.

2. octavo.

3. October.

4. Ohio.

5. Old.

6. Ontario.

7. Oregon.

---

O ⁹ American  

abbreviation

1. Grammar. object.

2. Old.

---

o- ¹⁰ American  

1. variant of oo-.

   oidium.

---

O ¹¹ American  

Symbol.

1. the fifteenth in order or in a series.

2. the Arabic cipher; zero.

3. (sometimes lowercase) the medieval Roman numeral for 11.

4. Physiology. a major blood group, usually enabling a person whose blood is of this type to donate blood to persons of group O, A, B, or AB and to receive blood from persons of group O.

5. Chemistry. oxygen.

6. Logic. particular negative.

---

o' ¹² American  

[uh, oh] / ə, oʊ /

preposition

1. a shortened form of of, as in o'clock or will-o'-the-wisp.

2. Chiefly Dialect. a shortened form of on.

---

O' ¹³ American  

1. a prefix meaning “descendant,” in Irish family names.

   O'Brien; O'Connor.

---

-o ¹⁴ American  

1. a suffix occurring as the final element in informal shortenings of nouns (ammo; combo; condo; limo; promo ); -o also forms nouns, usually derogatory, for persons or things exemplifying or associated with that specified by the base noun or adjective (cheapo; pinko; sicko; weirdo; wino ).

2. a suffix occurring in colloquial noun or adjective derivatives, usually grammatically isolated, as in address.

   cheerio; kiddo; neato; righto.

---

-o- ¹⁵ American  

1. the typical ending of the first element of compounds of Greek origin (as -i- is, in compounds of Latin origin), used regularly in forming new compounds with elements of Greek origin and often used in English as a connective irrespective of etymology.

   Franco-Italian; geography; seriocomic; speedometer.

---

O ¹ British  

symbol

1. chem oxygen

2. a human blood type of the ABO group See universal donor

3. logic a particular negative categorial proposition, such as some men are not married: often symbolized as SoP Compare A E I 2

---

abbreviation

1. slang offence

o ² British  

/ əʊ /

noun

1. the 15th letter and fourth vowel of the modern English alphabet

2. any of several speech sounds represented by this letter, in English as in code, pot, cow, move, or form

3. another name for nought

---

O ³ British  

/ əʊ /

interjection

1. a variant spelling of oh

2. an exclamation introducing an invocation, entreaty, wish, etc

   O God!

   O for the wings of a dove!

---

O'- ⁴ British  

prefix

1. (in surnames of Irish Gaelic origin) descendant of

   O'Corrigan

---

-o ⁵ British  

suffix

1. forming informal and slang variants and abbreviations, esp of nouns

   wino

   lie doggo

   Jacko

---

-o- ⁶ British  

1. used to connect elements in a compound word Compare -i-

   chromosome

   filmography

---

o- ⁷ British  

prefix

1. short for ortho-

---

o' ⁸ British  

/ ə /

preposition

1. informal shortened form of of

   a cup o' tea

---

Etymology

Origin of o.³

From the Latin word octārius

Origin of O.⁴

From the Latin word octārius

Origin of O⁵

First recorded in 1125–75; Middle English, from Old French, from Latin ō

Origin of o'¹²

From Middle English; by shortening

Origin of O'¹³

Representing Irish ó descendant, Old Irish au

Origin of -o¹⁴

Perhaps originally the interjection O, appended to words as in -o def. 2; as a derivational suffix reinforced by clipped forms of words with -o- as a linking element (e.g., photo, stereo ), by Rom nouns ending in o, and by personal nouns such as bimbo and bozo, of obscure origin

Origin of -o-¹⁵

Middle English (< Old French ) < Latin < Greek