Cambrian
Concise Oxford English Dictionary © 2008 Oxford University Press:
Cambrian /ˈkambrɪən/
▶adjective
- 1 (chiefly in names or geographical terms) Welsh.
- 2 Geology relating to or denoting the first period in the Palaeozoic era (between the Precambrian aeon and the Ordovician period, about 570 to 510 million years ago), a time when there was extensive invertebrate life.
– origin C17: from L. Cambria ‘Wales’, var. of Cumbria, from Welsh Cymry ‘Welshman’ or Cymru ‘Wales’.
'Cambrian' also found in these Oxford entries:

