/ ɝːbiəm /
Er · atomic number 68
Soft, lustrous, grayish, metallic element of the lanthanide series, symbol Er, atomic number 68, atomic weight 167.26. It occurs with the element yttrium or as a minute part of various minerals. It was discovered 1843 by Carl Mosander (1797–1858), and named for the town of Ytterby, Sweden, near which the lanthanides (rare-earth elements) were first found.A trivalent metallic element of the rare earth group; occurs with yttrium; SYN. Er, atomic number 68.