element, obtained 1906 from an earth discovered in 1886, the last to be extracted from the complex earth called yttria, and named dysprosia in reference to the difficulty of obtaining it, from Greek dysprositos "hard to get at, difficult of access," from dys- "bad" (see dys-) + prositos "approachable." With metallic element suffix -ium.
dysprosium dys·pro·si·um (dĭs-prō'zē-əm, -zhē-əm)
A soft, silvery rare-earth element used in nuclear research. Atomic number 66; atomic weight 162.50; melting point 1,411°C; boiling point 2,600°C; specific gravity 8.551; valence 3.
A soft, silvery metallic element of the lanthanide series. Because it has a high melting point and absorbs neutrons well, dysprosium is used to help control nuclear reactions. Atomic number 66; atomic weight 162.50; melting point 1,407°C; boiling point 2,600°C; specific gravity 8.536; valence 3. See Periodic Table.