noun Biochemistry.

a plasma protein involved in blood coagulation that on activation by factors in the plasma is converted to thrombin.

Nearby words

  1. prothonotary,
  2. prothonotary apostolic,
  3. prothonotary warbler,
  4. prothoracic gland,
  5. prothorax,
  6. prothrombin accelerator,
  7. prothrombin test,
  8. prothrombinase,
  9. protist,
  10. protista

Origin of prothrombin

First recorded in 1895–1900; pro-1 + thrombin

Also called thrombogen. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for prothrombin



biochem a zymogen found in blood that gives rise to thrombin on activationSee also phylloquinone
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medicine definitions for prothrombin




A glycoprotein formed by and stored in the liver and present in the blood plasma that is converted to thrombin in the presence of thromboplastin and calcium ion during blood clotting.factor II

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for prothrombin



A glycoprotein that is converted to thrombin during blood clotting. Prothrombin is formed by and stored in the liver.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.