a combining form with the meaning “muscle tension, nerve tension,” as specified by the initial element (hypertonia); used also in the formation of words that denote more generally a personality type or personality disorder (catatonia; somatotonia).
Origin of -tonia
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Degree or state of tonicity:myotonia.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.