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:
Share ion propulsion
Cite this Entry
“Ion propulsion.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ion%20propulsion. Accessed 7 Dec. 2021.
See Definitions and Examples »
Get Word of the Day daily email!
Farm Idioms Quiz
Test your knowledge - and maybe learn something along the way.
Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!
Top 10 Latin Phrases
From the week ending 12/3/2021
Don't argue with the dictionary
A simple trick to keep them separate
How 'literally' can mean "figuratively"
How to use a word that (literally) drives some pe...
The awkward case of 'his or her'
More than ROY G BIV
Take the quiz
How many do you know?
Test your knowledge - and maybe learn something a...