os

1 of 4

noun (1)

plural ossa ˈä-sə How to pronounce os (audio)
: bone

os

2 of 4

noun (2)

plural ora ˈȯr-ə How to pronounce os (audio)

Os

3 of 4

symbol

osmium

OS

4 of 4

abbreviation

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

Word History

Etymology

Noun (1)

Latin oss-, os — more at osseous

Noun (2)

Latin or-, os — more at oral

First Known Use

Noun (1)

15th century, in the meaning defined above

Noun (2)

1737, in the meaning defined above

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

Dictionary Entries Near os

Cite this Entry

“Os.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/os. Accessed 28 Mar. 2024.

Medical Definition

os

1 of 4 noun
plural ossa ˈäs-ə How to pronounce os (audio)

Os

3 of 4 symbol
osmium

OS

4 of 4 abbreviation
left eye
used in writing prescriptions
Etymology

Abbreviation

Latin oculus sinister

More from Merriam-Webster on os

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