Merriam-Webster Logo
SINCE 1828
Menu
dictionary thesaurus

phosphorus trioxide

noun

Definition of phosphorus trioxide

: a deliquescent volatile crystalline compound P4O6 that is made by burning phosphorus in a limited supply of air or oxygen, that reacts with cold water to form phosphorous acid, and that decomposes with hot water; tetra-phosphorus hexoxide

— called also phosphorous anhydride

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

  • More than 250,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

Learn More about phosphorus trioxide

Share phosphorus trioxide

Statistics for phosphorus trioxide

Look-up Popularity

Comments on phosphorus trioxide

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

Show Comments  Hide Comments 

WORD OF THE DAY

wherewithal

means, resources, or money

Get Word of the Day daily email!

Test Your Vocabulary

Homophone Quiz

  • three-bears-two-of-them-look-like-theyre-whispering-to-a-third-bear-who-looks-chuffed-to-be-the-center-of-attention
  • In order to judge how people felt, the senator's office hired a firm to take a ______.
True or False

Test your knowledge - and maybe learn something along the way.

TAKE THE QUIZ
Dictionary Devil

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

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Words at Play

Ask the Editors

Word Games