First Known Use: 15th century
Dictionary
1os
noun \ˈäs\
plural os·sa \ˈä-sə\
Definition of OS
: bone
ADVERTISEMENT
Origin of OS
Latin oss-, os — more at osseous
Other Anatomy Terms
2os
noun \ˈōs\
plural ora \ˈȯr-ə\
Definition of OS
: orifice
Origin of OS
Latin or-, os — more at oral
First Known Use: 1737
Other Anatomy Terms
Os
symbol
Definition of OS
osmium
OS
abbreviation
Definition of OS
1
[Latin oculus sinister] left eye
2
Old Style
3
operating system
4
out of stock
See OS defined for English-language learners
Other Anatomy Terms
Learn More About OS
ADVERTISEMENT
Seen & Heard
What made you want to look up os? Please tell us where you read or heard it (including the quote, if possible).