a suffix occurring in nouns that denote actions, conditions, or states (hypnosis; leukocytosis; osmosis), especially disorders or abnormal states (chlorosis; neurofibromatosis; tuberculosis).

Nearby words

  1. -orexia,
  2. -orial,
  3. -oriented,
  4. -ory,
  5. -ose,
  6. -osity,
  7. -ota,
  8. -ote,
  9. -otic,
  10. -our

Compare -otic.

Origin of -osis

on the model of Greek borrowings ending in Greek -ōsis, as sklērōsis sclerosis, derived orig. from verbs ending in the formative -o- (-ō- in noun derivatives), with the suffix -sis -sis

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for -osis


suffix forming nouns

indicating a process or statemetamorphosis
indicating a diseased conditiontuberculosis Compare -iasis
indicating the formation or development of somethingfibrosis

Word Origin for -osis

from Greek, suffix used to form nouns from verbs with infinitives in -oein or -oun

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

Word Origin and History for -osis


word-forming element expressing state or condition, in medical terminology denoting "a state of disease," from Latin -osis and directly from Greek -osis, formed from the aorist of verbs ending in -o. It corresponds to Latin -atio.

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for -osis



Condition; process; action:osmosis.
Diseased or abnormal condition:proptosis.
Increase; formation:leukocytosis.

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

Science definitions for -osis


A suffix that means:
Diseased condition, as in tuberculosis.
Condition or process, as in osmosis.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.