plural -s
: the primordial first substance from which according to some theories the elements are supposed to be formed
specifically : a primordial gas consisting of neutrons

Word History


Middle English, from Middle French ilem, probably from Medieval Latin hylem, accusative of hyle matter, from Latin, from Greek hylē

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!

Dictionary Entries Near ylem

Cite this Entry

“Ylem.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ylem. Accessed 25 Feb. 2024.

Love words? Need even more definitions?

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