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os

1
[ os ]
/ ɒs /
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noun, plural os·sa [os-uh]. /ˈɒs ə/.
Anatomy, Zoology. a bone.
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Origin of os

1
First recorded in 1540–50; from Latin os (inflectional stem oss- ) “bone”

Other definitions for os (2 of 9)

os2
[ os ]
/ ɒs /

noun, plural o·ra [awr-uh, ohr-uh]. /ˈɔr ə, ˈoʊr ə/.
Anatomy, Zoology. a mouth or orifice of the body.

Origin of os

2
First recorded in 1730–40; from Latin ōs (inflectional stem ōr- ) “mouth”

Other definitions for os (3 of 9)

os3
[ ohs ]
/ oʊs /

noun, plural o·sar [oh-sahr]. /ˈoʊ sɑr/.
Geology. an esker, especially when of great length.

Origin of os

3
First recorded in 1840–50 as osar (plural); from Swedish ås (plural åsar ) “ridge (of a hill),” from Old Norse áss “thick pole or main beam; rocky ridge”

Other definitions for os (4 of 9)

Os

Symbol, Chemistry. osmium.

Other definitions for os (5 of 9)

OS

abbreviation
Old Saxon. Also O.S.
Computers. operating system.

Other definitions for os (6 of 9)

o/s

(of the calendar) Old Style.
out of stock.
(in banking) outstanding.

Other definitions for os (7 of 9)

O/S

(of the calendar) Old Style.

Other definitions for os (8 of 9)

O.S.1

or o.s.


abbreviation
(in prescriptions) the left eye.

Origin of O.S.

1
From Latin oculus sinister

Other definitions for os (9 of 9)

O.S.2

abbreviation
Old Saxon. Also OS
(of the calendar) Old Style (def. 2).
ordinary seaman. Also o.s.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021

How to use os in a sentence

British Dictionary definitions for os (1 of 6)

os1
/ (ɒs) /

noun plural ossa (ˈɒsə)
anatomy the technical name for bone

Word Origin for os

C16: from Latin: bone; compare Greek osteon

British Dictionary definitions for os (2 of 6)

os2
/ (ɒs) /

noun plural ora (ˈɔːrə)
anatomy zoology a mouth or mouthlike part or opening

Word Origin for os

C18: from Latin

British Dictionary definitions for os (3 of 6)

os3
/ (əʊs) /

noun plural osar (ˈəʊsɑː)
another name for esker

Word Origin for os

C19 osar (pl), from Swedish ås (sing) ridge

British Dictionary definitions for os (4 of 6)

Os

the chemical symbol for
osmium

British Dictionary definitions for os (5 of 6)

OS

abbreviation for
Old School
Old Style (method of reckoning dates)
Ordinary Seaman
(in Britain) Ordnance Survey
outsize
Old Saxon (language)

British Dictionary definitions for os (6 of 6)

o.s.

OS or O/S


abbreviation for
out of stock
banking outstanding
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medical definitions for os (1 of 4)

os 11
[ ŏs ]

n. pl. o•ra (ôrə)
An opening into a hollow organ or canal.
The oral cavity; mouth.

Medical definitions for os (2 of 4)

os 22
[ ŏs ]

n. pl. os•sa (ŏsə)
Bone.

Medical definitions for os (3 of 4)

Os

The symbol for the elementosmium

Medical definitions for os (4 of 4)

OS

abbr.
oculus sinister (left eye)
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for os

Os

The symbol for osmium.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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