[uh-fer-uh-sis for 1; af-uh-ree-sis for 2]
  1. Also aphaeresis. the loss or omission of one or more letters or sounds at the beginning of a word, as in squire for esquire, or count for account.
  2. Medicine/Medical. the withdrawal of whole blood from the body, separation of one or more components, and return by transfusion of remaining blood to the donor.

Origin of apheresis

1605–15; < Late Latin aphaeresis < Greek aphaíresis a taking away, equivalent to aphairé(în) to take away (ap- ap-2 + haireîn to snatch) + -sis -sis
Related formsaph·e·ret·ic [af-uh-ret-ik] /ˌæf əˈrɛt ɪk/, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for apheresis



  1. the omission of a letter or syllable at the beginning of a word
  2. a method of collecting blood from donors that enables its different components, such as the platelets or plasma, to be separated out
Derived Formsapheretic or aphaeretic (ˌæfəˈrɛtɪk), adjective

Word Origin for apheresis

C17: via Late Latin from Greek, from aphairein to remove
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

apheresis in Medicine


  1. A procedure in which blood is drawn from a donor and separated into its components, some of which are retained, such as plasma or platelets, and the remainder returned by transfusion to the donor.hemapheresis
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.