“quaternary ammonium”

We have one entry that includes the term quaternary ammonium.

quaternary ammonium compound

noun

: any of numerous strong bases and their salts derived from ammonium by replacement of the hydrogen atoms with organic radicals and important especially as surface-active agents, disinfectants, and drugs

See the full definition

Word of the Day

Listen to the pronunciation of foist

See Definitions and Examples »

Test Your Vocabulary

Fashionable Words

  • dog-sunglasses-scarf
  • Which of these items is named for a deadly weapon?
Name That Thing

You know what it looks like… but what is it called?

TAKE THE QUIZ
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.

Pick the best words!

PLAY
Love words? Need even more definitions?

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

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Word Game Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
Missing Letter A crossword with a twist
winning words from the national spelling bee logo
Spelling Bee Quiz Can you outdo past winners of the National Spelli...