bitumen n.

a name given by the Roman writers to various hydrocarbons including asphalt and petroleum, mid-15c., from Latin bitumen "asphalt, mineral pitch," probably, via Oscan or Umbrian, from Celtic *betu- "birch, birch resin" (compare Gaulish betulla "birch," used by Pliny for the tree supposedly the source of bitumen). Related: Bituminate.