Merriam-Webster Logo
SINCE 1828
dictionary
thesaurus
view recents

isidium

noun
Save Word
isid·​i·​um | \ īˈsidēəm \
plural isidia\ -​ēə \

Definition of isidium

: an outgrowth from the surface of the thallus in certain lichens that resembles a soredium

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!

History and Etymology for isidium

New Latin, from Isidium, supposed genus of lichens, irregular from Isis genus of gorgonians + Greek eidos form; from the resemblance of lichens that have isidia to gorgonians

Keep scrolling for more

Learn More about isidium

Statistics for isidium

Cite this Entry

“Isidium.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/isidium. Accessed 20 Jan. 2021.

Comments on isidium

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

Show Comments  Hide Comments 

WORD OF THE DAY

gulosity

Listen to the pronunciation of gulosity

See Definitions and Examples »

Test Your Vocabulary

Words of Snow and Ice Quiz

  • image1037863653
  • Which of the following refers to thin, bending ice, or to the act of running over such ice?
True or False

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

TAKE THE QUIZ
Typeshift

Anagram puzzles meet word search.

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
Ask the Editors
Word Games