O

¹

or o

[ oh ]

noun

, plural O's or Os; o's or os or 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

Chemistry.

1. an abridgment of ortho-.

o.

³

abbreviation for

1. pint.

O.

⁴

abbreviation for

1. (in prescriptions) a pint.

O

⁵

[ oh ]

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

1. variant of ob- before m:

   omission.

o.

⁷

abbreviation for

1. octavo.
2. off.
3. old.
4. only.
5. order.
6. Baseball. out; outs.

O.

⁸

abbreviation for

1. Ocean.
2. octavo.
3. October.
4. Ohio.
5. Old.
6. Ontario.
7. Oregon.

O

⁹

abbreviation for

1. Grammar. object ( def 7 ).
2. Old.

o-

¹⁰

1. variant of oo-:

   oidium.

O

¹¹

Symbol.

1. the fifteenth in order or in a series.
2. the Arabic cipher; zero.
3. (sometimes lowercase) the medieval Roman numeral for 11. Compare Roman numerals ( def ).
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. Compare ABO system ( def ).
5. Chemistry. oxygen.
6. Logic. particular negative.

o'

¹²

[ uh, oh ]

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

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

   O'Brien; O'Connor.

-o

¹⁴

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

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

prefix

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

   O'Corrigan

-o

²

suffix

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

   wino

   lie doggo

   Jacko

-o-

³

connective vowel

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

   filmography

   chromosome

O

⁴

symbol for

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 for

1. slang.
   offence

O

⁵

/ əʊ /

interjection

1. a variant spelling of oh
2. an exclamation introducing an invocation, entreaty, wish, etc

   O for the wings of a dove!

   O God!

o-

⁶

prefix

1. short for ortho-

o

⁷

/ 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'

⁸

/ ə /

preposition

1. informal.
   shortened form of of

   a cup o' tea

Word History and Origins

Origin of O¹

From the Latin word octārius

Origin of O²

From the Latin word octārius

Origin of O³

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

Origin of O⁴

From Middle English; by shortening

Origin of O⁵

Representing Irish ó descendant, Old Irish au

Origin of O⁶

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 O⁷

Middle English (< Old French ) < Latin < Greek

Word History and Origins

Origin of O¹

from Irish Gaelic ó, ua descendant

Origin of O²

probably special use of oh

Origin of O³

from Greek, stem vowel of many nouns and adjectives in combination

Origin of O⁴

(for sense 3) from Latin ( neg ) o I deny