Definition of rubian in US English:

rubian

noun

Chemistry
rare, historical
  • A brownish-yellow resinous substance isolated from madder root, subsequently shown to consist of a mixture of glycosides of alizarin and other compounds.

Origin

Mid 19th century. From classical Latin rubia madder + -an, after German Rubian.

Pronunciation

rubian

/ˈruːbɪən/