Merriam-Webster Logo
SINCE 1828
Menu
×

An Encyclopædia Britannica Company

See What's Trending Now See More Trending Words

tonus

play
noun to·nus \ ˈtō-nəs \

Definition of tonus

:tone 9b; especially :a state of partial contraction characteristic of normal muscle

Read the Latest from M-W

alt-59c52d6ee2f72
Breathing Life Into 'Inspire'
young-plant-shoots
Merriam-Webster's New Words Quiz—Fall 2017 Edition!
alt-59c448f88ea38
Trending: Kim Jong Un: Trump a 'Dotard'
video-title-words-of-the-year-1066
Words of the Year: 1066

Origin and Etymology of tonus

New Latin, from Latin, tension, tone

Medical Dictionary

tonus

play
noun to·nus \ ˈtō-nəs \

medical Definition of tonus

1 :tone 2a
2 :a state of partial contraction that is characteristic of normal muscle, is maintained at least in part by a continuous bombardment of motor impulses originating reflexly, and serves to maintain body posture — called also muscle tone; compare clonus

Learn More about tonus

  1. See words that rhyme with tonus

Seen and Heard

What made you want to look up tonus? Please tell us where you read or heard it (including the quote, if possible).

show hide

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

WORD OF THE DAY

legerity

play

alert quickness of mind or body

Get Word of the Day daily email!

TRENDING NOW

  1. dotage, dotard a state or period of senile decay

  2. otherwise "in other respects"

  3. federalism Graham says bill gives power to states

  4. bodega "Don’t mess with the beloved bodega."

  5. carceral Of, relating to, or suggesting a jail or prison

SEE ALL

BROWSE DICTIONARY

tonus

Test Your Vocabulary

Merriam-Webster's New Words Quiz—Fall 2017 Edition!

  • young-plant-shoots
  • Which of the following is a new sense of the word bunny?
True or False

Test your knowledge - and maybe learn something along the way.

TAKE THE QUIZ
Syn City

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Words at Play

alt-59c52d6ee2f72
Breathing Life Into 'Inspire'

The word's origins are quite literal

alt-59c4207ecf106
Let's Talk 'Tea'

Spill it, sip it: just make it hot.

image1644821030
8 Words and Phrases from Boxing and Wrestling

Common terms that come from boxing and wrestling

alt-59c2960017c94
The Ambiguity of Pushing 'Up' and 'Back'

When you push a meeting, where does it go?

Ask the Editors

video-title-words-of-the-year-1066
Words of the Year: 1066

Or, Why Pig Meat is Called 'Pork' and Cow Meat is Called 'Beef'

payday
How Often Is 'Biweekly'?

Don't get us started on 'bimonthly'

video-irregardless-grammar-peeve-blend-of-the-synonyms-irrespective-and-regardless
Irregardless

It is in fact a real word (but that doesn't mean you should use it).

video-moose-goose-weird-plurals
Weird Plurals

One goose, two geese. One moose, two... moose. What's up with that?

Word Games

young-plant-shoots
Merriam-Webster's New Words Quiz—Fall 2017 Edition!

You're going to have to memorize the dictionary again.

Take the quiz
stylized-drawing-of-woman-pole-vaulting-across-gap-to-get-trophy
Challenging Vocabulary Quiz Returns!

No tricks, just difficult words.

Take the quiz
True or False
True or False?

Test your knowledge - and maybe learn something along the way.

Take the quiz
Syn City
Syn City

Build a city of skyscrapers—one synonym at a time.

Play the game