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

vitamin K

noun

Definition of vitamin K

  1. 1 :  either of two naturally occurring fat-soluble vitamins C31H46O2 and C41H56O2 essential for the clotting of blood because of their role in the production of prothrombin —called also vitamin K1, vitamin K2

  2. 2 :  any of several synthetic compounds closely related chemically to natural vitamins K1 and K2 and of similar biological activity



Origin of vitamin k

from the initial letter of Dan & Swedish koagulation coagulation, Norwegian koagulasjon & German Koagulation


First Known Use: circa 1935


Medical Dictionary

vitamin K

noun

Medical Definition of vitamin K

  1. 1:  either of two naturally occurring fat-soluble vitamins that are essential for the clotting of blood because of their role in the production of prothrombin in the liver and that are used in preventing and treating hypoprothrombinemia and hemorrhage:a:  a yellow oily naphthoquinone C31H46O2 that is obtained especially from alfalfa or made synthetically and that has a fast, potent, and prolonged biological effect, is effective orally, and is useful especially in treating hypoprothrombinemia induced by anticoagulant drugs—called also phylloquinone, phytonadione, vitamin K1; see mephytonb:  a pale yellow crystalline naphthoquinone C41H56O2 that is obtained especially from putrefied fish meal and is synthesized by various bacteria (as in the intestines of humans and higher animals) and that is much more unsaturated than vitamin K1 and slightly less active biologically—called also menaquinone, vitamin K2

  2. 2:  any of several synthetic compounds that are closely related chemically to vitamins K1 and K2 but are simpler in structure and that have similar biological activity; especially :  menadione




Learn More about vitamin k


Seen and Heard

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

WORD OF THE DAY

a timid, meek, or unassertive person

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

alt-5746713d76276

Which of these is a synonym of nonplus?

reduce disapprove perplex soothe
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