Merriam-Webster Logo
SINCE 1828
Menu
×

An Encyclopædia Britannica Company

See What's Trending Now See More Trending Words

free piston

noun

Definition of free piston

:a combination of two pistons that are usually of different diameters, are rigidly attached to the same piston rod, work in different cylinders without external connection, and are used in some pumps and pressure gauges

From the M-W Editors

image1644821030
These Are Fighting Words
alt-59c94ad823f29
'Meat Sweats': The Cookout's Worst Nightmare
video-title-words-of-the-year-1066
Words of the Year: 1066
young-plant-shoots
Merriam-Webster's New Words Quiz—Fall 2017 Edition!

There's more!

Love words? You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

  • More than 250,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!
Already a subscriber? Log in.

Seen and Heard

What made you want to look up free piston? 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

anathematize

play

to curse or denounce

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

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-59c94ad823f29
'Meat Sweats': The Cookout's Worst Nightmare

They're real, but is meat the cause?

alt-59c919f342079
'Diffuse' vs. 'Defuse'

Let us defuse the situation.

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.

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
Name That Thing
Name That Thing

Test your visual vocabulary with our 10-question challenge!

Take the quiz
Word Winder's CrossWinder
Word Winder's CrossWinder

A game of winding words.

Play the game