The·​si·​um | \ ˈthēsēəm, thə̇ˈsīəm\

Definition of Thesium 

: a large genus of Old World root-parasitic herbs of the family Santalaceae with small linear or scalelike leaves and diclinous flowers — see bastard toadflax

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 Thesium

New Latin, from Latin thesium, thesion bastard toad flax, from Greek thēseion, probably from neuter of thēseios of Theseus, from Thēseus Theseus, mythological Greek hero

Keep scrolling for more

Learn More about Thesium

Statistics for Thesium

Look-up Popularity

Comments on Thesium

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


marked by shyness and lack of polish

Get Word of the Day daily email!

Test Your Vocabulary

Liar, Liar Quiz

  • alt-5761dbe2ba986
  • Someone who pretends to be sick in order to avoid work is a:
Name That Thing

Test your visual vocabulary with our 10-question challenge!

Syn City

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


Love words? Need even more definitions?

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