a combining form with the meanings “large, great, grand,” “abnormally large,” used in the formation of compound words: megalopolis; megalocardia.



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Also especially before a vowel, megal-.
Compare mega-.

Origin of megalo-

<Greek, combining form of megal- (stem of mégas) great, large Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2021


What does megalo- mean?

Megalo- is a combining form used like a prefix meaning “large, great, grand, abnormally large.” It is used in many scientific and medical terms.

Megalo- ultimately comes from the Greek mégas, meaning “great, large.”

What are variants of megalo-?

When combined with words or word elements that begin with a vowel, megalo- becomes megal-, as in megalopsia.

Another variant of megalo- are you may be familiar with is mega-, as in megaphone or megabyte. Mega- is also used as a unit of measure prefix to indicate a fact of one million (e.g., megahertz).

Corresponding forms of megalo- combined to the end of words are -megaly and -megalia.

Examples of megalo-

You may have come across the combining form megalo- from the word megalomania. In psychiatry, megalomania refers to delusions of greatness, wealth, and the like. The term is also more generally used to mean “an obsession with doing extravagant or grand things” and “extreme self-importance.”

The combining form megalo- means “abnormally large,” as we’ve seen. The combining form -mania means “excessive excitement or enthusiasm.” Megalomania has a little sense of “great enthusiasm.”

What are some words that use the combining form megalo-?

What are some other forms that megalo- may be commonly confused with?

Break it down!

The combining form -polis means “city.” With this in mind, what is a megalopolis?

British Dictionary definitions for megalo-


before a vowel megal-

combining form

indicating greatness, or abnormal sizemegalopolis; megaloblast

Word Origin for megalo-

from Greek megas great
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 megalo-



Large; of exaggerated size or greatness:megalocephaly.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.