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

Origin of -osis

On the model of Greek borrowings ending in Greek -ōsis, as sklērōsissclerosis, derived originally 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. 2022

How to use -osis in a sentence

  • The surgeons had called it something ending in osis and prescribed finally "light duty."

    Command|William McFee

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

Medical 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.

Scientific 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.