fermium

UK: /ˈfɜːmɪəm/ US: (fûr′mē əm)

WordReference Random House Unabridged Dictionary of American English © 2025

fer•mi•um  (fûr′mē əm), n. [Chem., Physics.]

1. Chemistry, Physics a transuranic element. Symbol: Fm;
   at. no.: 100.

• 1950–55; named after English. Fermi; see -ium

Collins Concise English Dictionary © HarperCollins Publishers::

fermium / ˈfɜːmɪəm/ noun

1. a transuranic element artificially produced by neutron bombardment of plutonium. Symbol: Fm; atomic no: 100; half-life of most stable isotope, ²⁵⁷Fm: 80 days (approx.)

Etymology: 20th Century: named after Enrico Fermi