Quizzes & Games
Word of the Day
Video
New Words
My Favorites
View your list of saved words.
(You can log in using Facebook.)

arsenious oxide

noun

Definition of ARSENIOUS OXIDE

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

Take Our 10-Question Quiz

Hear It, Spell It »

Take It Now »

Take the Quiz »

Get Our Free Apps

Voice Search, Favorites,
Word of the Day, and More

iPhone | iPad | Android | More

Join Us on FB & Twitter

Get the Word of the Day and More

Facebook | Twitter

The Merriam-Webster
Unabridged Dictionary

Online access to a
legendary resource
Log In or Sign Up »

Learning English?
We can help.

Visit our free site designed
especially for learners and
teachers of English
LearnersDictionary.com »

Our Dictionary,
On Your Devices

Merriam-Webster,
With Voice Search
Get the Free Apps! »

Merriam-Webster's
Visual Dictionaries

The new edition of the
remarkable reference
features 8,000
illustrations.
Learn More »

Join Us

Bookstore: Digital and Print

Merriam-Webster references for Mobile, Kindle, print, and more. See all »

Other Merriam-Webster Dictionaries

Browse the Dictionary

Browse the Thesaurus

Browse the Spanish-English Dictionary

Browse the Medical Dictionary

Browse the Concise Encyclopedia