Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Medical
  • Scrabble
  • Spanish Central
  • Learner's Dictionary
1

os

play
noun \ˈäs\

Definition of os

plural ossa play \ˈä-sə\

  1. :  bone



Origin of os

Latin oss-, os — more at osseous


First Known Use: 15th century

Rhymes with os


2

os

play
noun \ˈōs\

Definition of os

plural ora play \ˈȯr-ə\

  1. :  orifice



Origin of os

Latin or-, os — more at oral


First Known Use: 1737

Rhymes with os


Os

symbol

Definition of Os

  1. osmium



Other Chemical Engineering Terms


OS

abbreviation

Definition of OS

  1. 1 [Latin oculus sinister] left eye

  2. 2 Old Style

  3. 3 operating system

  4. 4 out of stock




Learn More about os


Seen and Heard

What made you want to look up os? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

the Celtic May Day festival

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

image567572573

Which of these is a synonym of unctuous?

maudlin prompt angry oily
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ