factor IX

play
noun \ -ˈnīn \

Definition of factor IX

:a clotting factor that activates factor VIII and whose deficiency is associated with hemophilia called also Christmas factor

First Known Use of factor ix

1955


Medical Dictionary

factor IX

play
noun \ -ˈnīn \

medical Definition of factor IX

:a clotting factor that activates factor VIII and whose absence is associated with hemophilia B called also autoprothrombin II, Christmas factor

Seen and Heard

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

Love words? Need even more definitions?

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

WORD OF THE DAY

of yeast or being unsettled or frivolous

Get Word of the Day daily email!

Test Your Vocabulary

Merriam-Webster's New Words Quiz—Fall 2017 Edition!

  • young-plant-shoots
  • Which of the following is a new sense of the word bunny?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
Word Winder's CrossWinder

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!