What does apheresis mean?
Apheresis is a noun with two distinct senses sharing one Greek root. Its dominant modern meaning is medical: an apheresis procedure withdraws blood from a donor or patient, separates out a specific component such as plasma, platelets, or white blood cells, removes that component, and returns the remaining blood to the body. It underlies familiar practices like platelet donation and therapeutic plasma exchange, and related terms include plasmapheresis and leukapheresis. A second, older sense belongs to linguistics, where apheresis denotes the loss of one or more initial sounds or syllables from a word over time — the mirror image of apocope, which trims word endings. The word comes from the Greek aphairesis, meaning a taking away or removal, via Latin. Because of its clinical dominance, apheresis today appears mainly in hospital, laboratory, and technical writing, though readers of etymology and phonetics will meet it describing how words shed their opening syllables as languages evolve.
A medical procedure in which blood is drawn from a person, separated into its components, one component is selectively removed, and the remaining blood is returned to the circulation.
"The clinic scheduled him for apheresis twice a week to lower his dangerously high white-cell count."
Specialised forms are named after the component removed, e.g. plasmapheresis, plateletpheresis, leukapheresis, erythrocytapheresis.
The loss or omission of one or more sounds, especially an initial vowel, from the beginning of a word.
"The word 'round' shows apheresis relative to its ancestor 'around', having lost its initial unstressed vowel."
Chiefly used in historical linguistics and phonology; contrast with apocope (loss of final sounds).
The plural is rare because apheresis usually appears as a single procedure or concept; it occurs mainly when referring collectively to multiple procedures or instances.
"The transfusion unit performed several aphereses that morning."
The same word names both a life-saving medical procedure that filters your blood — and the reason 'specialty' became 'spesh' when spoken quickly.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of apheresis
Apheresis derives from the ancient Greek noun aphairesis, formed from apo- (away from) plus hairein (to take), literally meaning 'a taking away'. The term passed into Latin and then into English in the early seventeenth century, where it was first applied in rhetoric and grammar to the removal of something — including the dropping of a word's initial letters or sounds. In the twentieth century, as techniques for separating blood into its components were developed, physicians borrowed the term to describe the mechanical removal of a blood constituent, and this medical usage has become by far the most common today. It shares its Greek origin with cognate terms of removal such as apocope and syncope.
Related word forms
How apheresis is actually used
Today the word overwhelmingly refers to the medical procedure, and it appears almost exclusively in clinical, scientific, or technical registers. The linguistic sense is largely confined to phonetics, historical linguistics, and dictionaries. In British English an older spelling, aphaeresis (with the digraph ae), persists in some references, but the spelling given here is standard in American English and increasingly common elsewhere.
Easily confused with apheresis
"Hemapheresis" is an older term for the same blood-separation procedure; "apheresis" is now the standard name, while in linguistics apheresis refers to loss of word-initial sounds.
Apocope is the loss of sounds at the END of a word, whereas linguistic apheresis is the loss of sounds at the BEGINNING of a word.