Webster's New World Medical Dictionary

1 TMMedical DictionaryThird EditionFrom the Doctors and Experts at WebMD 01_189283 4/25/08 6:40 PM Page s New World Medical Dictionary , Third EditionCopyright 2008 All rights by Wiley Publishing, Inc., Hoboken, New JerseyNo part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or byany means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permittedunder Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to theCopyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978)646-8600, or on the web at Requests to the Publisher for permission should beaddressed to the Legal Department, Wiley Publishing, Inc., 10475 Crosspoint Blvd., Indianapolis, IN 46256,(317) 572-3447, fax (317) 572-4355, or online at publisher and the author make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation warranties of fitness for a particular purpose.

2 No warranty may be created or extended by sales orpromotional materials. The advice and strategies contained herein may not be suitable for every work is sold with the understanding that the publisher is not engaged in rendering legal, accounting, orother professional services. If professional assistance is required, the services of a competent professionalperson should be sought. Neither the publisher nor the author shall be liable for damages arising herefrom. The fact that an organization or Website is referred to in this work as a citation and/or a potentialsource of further information does not mean that the author or the publisher endorses the information theorganization or Website may provide or recommendations it may make. Further, readers should be awarethat Internet Websites listed in this work may have changed or disappeared between when this work waswritten and when it is : Wiley, the Wiley Publishing logo, webster s New World , and all related trademarks, logos andtrade dress are trademarks or registered trademarks of John Wiley & Sons, Inc.

3 And/or its affiliates. Allother trademarks are the property of their respective owners. Wiley Publishing, Inc. is not associated withany product or vendor mentioned in this general information on our other products and services or to obtain technical support, please contactour Customer Care Department within the at 800-762-2974, outside the at 317-572-3993, or also publishes its books in a variety of electronic formats. Some content that appears in print may notbe available in electronic books. For more information about Wiley products, please visit our web site of Congress Cataloging-in-Publication Data is available from the publisher upon : 978-0-470-18928-3 Printed in the United States of America10987654321 Book production by Wiley Publishing, Inc. Composition Services01_189283 4/18/08 10:03 PM Page DictionaryThird EditionFrom the Doctors and Experts at WebMD 01_189283 4/25/08 6:40 PM Page s New World Medical Dictionary , Third EditionCopyright 2008 All rights by Wiley Publishing, Inc.

4 , Hoboken, New JerseyNo part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or byany means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permittedunder Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to theCopyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978)646-8600, or on the web at Requests to the Publisher for permission should beaddressed to the Legal Department, Wiley Publishing, Inc., 10475 Crosspoint Blvd., Indianapolis, IN 46256,(317) 572-3447, fax (317) 572-4355, or online at publisher and the author make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation warranties of fitness for a particular purpose.

5 No warranty may be created or extended by sales orpromotional materials. The advice and strategies contained herein may not be suitable for every work is sold with the understanding that the publisher is not engaged in rendering legal, accounting, orother professional services. If professional assistance is required, the services of a competent professionalperson should be sought. Neither the publisher nor the author shall be liable for damages arising herefrom. The fact that an organization or Website is referred to in this work as a citation and/or a potentialsource of further information does not mean that the author or the publisher endorses the information theorganization or Website may provide or recommendations it may make. Further, readers should be awarethat Internet Websites listed in this work may have changed or disappeared between when this work waswritten and when it is : Wiley, the Wiley Publishing logo, webster s New World , and all related trademarks, logos andtrade dress are trademarks or registered trademarks of John Wiley & Sons, Inc.

6 And/or its affiliates. Allother trademarks are the property of their respective owners. Wiley Publishing, Inc. is not associated withany product or vendor mentioned in this general information on our other products and services or to obtain technical support, please contactour Customer Care Department within the at 800-762-2974, outside the at 317-572-3993, or also publishes its books in a variety of electronic formats. Some content that appears in print may notbe available in electronic books. For more information about Wiley products, please visit our web site of Congress Cataloging-in-Publication Data is available from the publisher upon : 978-0-470-18928-3 Printed in the United States of America10987654321 Book production by Wiley Publishing, Inc. Composition Services01_189283 4/18/08 10:03 PM Page , a part of the WebMD network, we continue to foster the concept that you, thereaders, are truly interested in understanding health issues and Medical concepts.

7 Accordingly, wehave addressed the Medical terms in this Dictionary with sensitivity to potential concerns of thosewho are acutely or chronically confronting disease or health concerns. We are grateful for yourinterest in health topics as it is a driving force for the development of the webster s New WorldMedical Dictionary , Third behalf of the division of WebMD, we wish to thank the staff at Wiley Publishing,Inc., especially Roxane Cerda and Suzanne Snyder, for bringing this Dictionary to those who need also thank the officers of , particularly Gene Lu and David Sorenson, who havesupported the development of this excellence of the technical and editorial staffs at greatly facilitated this entireproject. Dan Griffith and Michael Cupp provided the unique publishing software that made it all pos-sible. Cynde Lee, Kelly McKiernan, and Tanya Buchanan have performed magnificently in managingthe vast amount of content and communication between authors and editors.

8 David Sorenson hasbeen an inspirational catalyst for motivation and consistent superior quality. William C. Shiel, Jr., MD, FACP, FACR, thanks his children, Cara Shiel Krenn, Daniel, and Timothy fortheir support. He also acknowledges the support and encouragement of his parents, William andVirginia Shiel, as well as his dear mother-in-law, Helen Stark. With infinite gratitude and love hethanks his wife, Catherine, for her support, love, and editing. With gratitude he acknowledges theHerculean efforts of Frederick Hecht, MD, FAAP, FACMG in developing previous editions of this dic-tionary. And, with admiration beyond words, he thanks his dear friend, colleague, and co-founderof , Dennis Lee, Conrad St ppler, MD wishes to thank her husband, Hubert St ppler, and her children,Johannes, Anna, and Tilman, for their enduring support, love, and patience. She also gratefullyacknowledges the support and encouragement of her parents, Kathryn B.

9 Conrad and the late HenryE. Conrad, you all. William C. Shiel, Jr., MD, FACP, FACR Melissa Conrad St ppler, MD01_189283 4/18/08 10:03 PM Page StaffCo-Editors-in-ChiefWilliam C. Shiel, Jr., MD, FACP, Conrad St ppler, EditorsDennis Lee, W. Marks, Mathur, MD, FRCP(C) ManagersCynde LeeKelly DevelopmentDavid SorensonGene Additional Free Content OnlineAs an added bonus to this fully revised third edition of the webster s New World Medical Dictionary ,you can visit the companion website at You ll find a free PDF Healthcare Guide to help you get the most out of your personal Medical can also listen to podcasts from Dr. William Shiel and Dr. Melissa St ppler, the co-editors of theWebster s New World Medical Dictionary ,in which they discuss strategies to help you better com-municate with your doctors and 4/18/08 10:03 PM Page the AuthorsWilliam C. Shiel, Jr., MD, FACP, FACR, Co-Editor-in-ChiefWilliam C. Shiel, Jr., MD, FACP, FACR, received a bache-lor of science degree with honors from the University ofNotre Dame.

10 There he was involved in research in radi-ation biology and received the Huisking graduating from St. Louis University School ofMedicine, he completed his internal medicine resi-dency and rheumatology fellowship at University ofCalifornia, Irvine. He is board certified in internal med-icine and rheumatology and is a fellow of the AmericanColleges of Physicians and Rheumatology. Dr. Shiel is inactive practice in the field of rheumatology at theArthritis Center of Southern Orange County, is currently an active associate clinical professor ofmedicine at University of California, Irvine. He hasserved as chair of the Department of Internal Medicine at Mission Hospital Regional Medical Centerin Mission Viejo, California. Dr. Shiel has authored numerous articles on subjects related to arthri-tis for prestigious peer-reviewed Medical journals, as well as many expert Medical -legal reviews. Hehas lectured in person and on television both for physicians and the community.