[too-mer, tyoo-]
  1. a swollen part; swelling; protuberance.
  2. an uncontrolled, abnormal, circumscribed growth of cells in any animal or plant tissue; neoplasm.
  3. Archaic.
    1. inflated pride; haughtiness.
    2. pompous language; bombast.
Also especially British, tu·mour.

Origin of tumor

1535–45; < Latin: a swelling, swollen state, equivalent to tum(ēre) to swell + -or -or1
Related formstu·mor·like, adjectivetu·mor·ous, tu·mor·al, adjectivean·ti·tu·mor, adjective, nounan·ti·tu·mor·al, adjectivenon·tu·mor·ous, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for tumour

Historical Examples of tumour

British Dictionary definitions for tumour


US tumor

  1. pathol
    1. any abnormal swelling
    2. a mass of tissue formed by a new growth of cells, normally independent of the surrounding structures
  2. obsolete pompous style or language
Derived Formstumorous or tumoral, adjective

Word Origin for tumour

C16: from Latin, from tumēre to swell
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 tumour



1540s, from Latin tumor "swelling, condition of being swollen," from tumere "to swell" (see thigh).

Online Etymology Dictionary, © 2010 Douglas Harper

tumour in Medicine


  1. An abnormal growth of tissue resulting from uncontrolled, progressive multiplication of cells and serving no physiological function; a neoplasm.
  2. A swollen part; a swelling.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

tumour in Science


  1. See neoplasm. See Note at cancer.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

tumour in Culture


An abnormal mass of new tissue growth that serves no function in the body. Tumors are usually classified as benign or malignant and are often caused by cancer.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.