Degree or state of tonicity: myotonia.
[New Latin, from Latin tonus; see tone.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
a combining form meaning “muscle tension,” “nerve tension” (hypertonia; vagotonia), “a muscle tension disorder” (catatonia)
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.