Merriam-Webster Logo
SINCE 1828
Menu
×

An Encyclopædia Britannica Company

See What's Trending Now See More Trending Words

ultrabasic

play
adjective ul·tra·ba·sic \ ˌəl-trə-ˈbā-sik \

Definition of ultrabasic

:extremely basic
  • an ultrabasic system
; specifically :very low in silica and rich in iron and magnesium minerals
  • dunite and peridotite are ultrabasic rocks
—

ultrabasic

noun

Explore M-W

video-title-words-of-the-year-1066
Words of the Year: 1066
image1644821030
These Are Fighting Words
young-plant-shoots
Merriam-Webster's New Words Quiz—Fall 2017 Edition!
alt-59c52d6ee2f72
Breathing Life Into 'Inspire'

Origin and Etymology of ultrabasic

International Scientific Vocabulary

Seen and Heard

What made you want to look up ultrabasic? 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

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
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