What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
noun
mass nounThe chemical element of atomic number 65, a silvery-white metal of the lanthanide series.
- ‘Green light is also emitted from some lanthanide elements: lanthanum, cerium, and terbium.’
Origin
Mid 19th century: modern Latin, from Ytterby, the name of a village in Sweden where it was discovered. Compare with erbium and ytterbium.
