\ ˈäs How to pronounce os (audio) \
plural ossa\ ˈä-​sə How to pronounce os (audio) \

Definition of os

 (Entry 1 of 4)

: bone
\ ˈōs How to pronounce os (audio) \
plural ora\ ˈȯr-​ə How to pronounce os (audio) \

Definition of os (Entry 2 of 4)

Os

symbol

Definition of Os (Entry 3 of 4)

osmium

Definition of OS (Entry 4 of 4)

1 [Latin oculus sinister] left eye
2 Old Style
3 operating system
4 out of stock

First Known Use of os

Noun (1)

15th century, in the meaning defined above

Noun (2)

1737, in the meaning defined above

History and Etymology for os

Noun (1)

Latin oss-, os — more at osseous

Noun (2)

Latin or-, os — more at oral

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Time Traveler for os

Time Traveler

The first known use of os was in the 15th century

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Cite this Entry

“Os.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/os. Accessed 13 Jun. 2021.

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More Definitions for os

os

noun
\ ˈäs How to pronounce os (audio) \
plural ossa\ ˈäs-​ə How to pronounce os (audio) \

Medical Definition of os

 (Entry 1 of 4)

: bone — see os calcis, os coxae

os

noun
\ ˈōs How to pronounce os (audio) \
plural ora\ ˈōr-​ə, ˈȯr-​ə How to pronounce os (audio) \

Medical Definition of os (Entry 2 of 4)

Os

symbol

Medical Definition of Os (Entry 3 of 4)

osmium

Medical Definition of OS (Entry 4 of 4)

left eye used in writing prescriptions

History and Etymology for os

Abbreviation

Latin oculus sinister

More from Merriam-Webster on os

Nglish: Translation of os for Spanish Speakers

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