os

¹ American  

[os] / ɒs /

noun

plural

ossa

1. Anatomy, Zoology. a bone.

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os ² American  

[os] / ɒs /

noun

plural

ora

1. Anatomy, Zoology. a mouth or orifice of the body.

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os ³ American  

[ohs] / oʊs /

noun

plural

osar

1. Geology. an esker, especially when of great length.

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Os ⁴ American  

1. Symbol, Chemistry. osmium.

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OS ⁵ American  

abbreviation

1. Old Saxon. Also O.S.

2. Computers. operating system.

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o/s ⁶ American  

1. (of the calendar) Old Style.

2. out of stock.

3. (in banking) outstanding.

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O/S ⁷ American  

1. (of the calendar) Old Style.

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O.S. ⁸ American  

Or o.s.

abbreviation

1. (in prescriptions) the left eye.

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O.S. ⁹ American  

abbreviation

1. Old Saxon. Also OS

2. (of the calendar) Old Style.

3. ordinary seaman. Also o.s.

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OS ¹ British  

abbreviation

1. Old School

2. Old Style (method of reckoning dates)

3. Ordinary Seaman

4. (in Britain) Ordnance Survey

5. outsize

6. Old Saxon (language)

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o.s. ² British  

abbreviation

1. out of stock

2. banking outstanding

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Os ³ British  

symbol

1. osmium

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os ⁴ British  

/ ɒs /

noun

1. anatomy the technical name for bone

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os ⁵ British  

/ ɒs /

noun

1. anatomy zoology a mouth or mouthlike part or opening

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os ⁶ British  

/ əʊs /

noun

1. another name for esker

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Etymology

Origin of os¹

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

Origin of os²

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

Origin of os³

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”

Origin of O.S.⁸

From Latin oculus sinister

Example Sentences

A new Longevity Preparedness Index from John Hancock and MIT AgeLab os based on a survey of over 1,300 adults and focused on eight areas such as finance, home, health and community.

From MarketWatch • Dec. 12, 2025

She first broke through with 2016’s “Remonta,” an album she recorded with her former band Liniker e os Caramelows.

From Los Angeles Times • Oct. 8, 2025

Mas o escopo completo desses impactos está se revelando nos dados que os Juruna e seus colaboradores cientistas vêm coletando.

From Science Magazine • Jan. 5, 2023

“Sabíamos que os peixes sofreriam com um fluxo de rio que não é mais natural.”

From Science Magazine • Jan. 5, 2023

You could talk to him about os and argos, suet and grease, croteys, fewmets and fiants, but he only looked polite.

From "The Once and Future King" by T. H. White