the typical ending of the first element of compounds of Greek origin (as -i- is, in compounds of Latin origin), used regularly in forming new compounds with elements of Greek origin and often used in English as a connective irrespective of etymology: Franco-Italian; geography; seriocomic; speedometer.

Nearby words

  1. -ness,
  2. -nik,
  3. -noia,
  4. -nomy,
  5. -o,
  6. -oate,
  7. -ock,
  8. -ocracy,
  9. -ode,
  10. -odont

Compare -i-.

Origin of -o-

Middle English (< Old French) < Latin < Greek

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

British Dictionary definitions for -o-


connective vowel

used to connect elements in a compound wordchromosome; filmography Compare -i-

Word Origin for -o-

from Greek, stem vowel of many nouns and adjectives in combination

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

Medicine definitions for -o-


Used as a connective to join word elements:acidophilic.

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