Word Study
buna
CIDE DICTIONARY
buna, n. [trademark.].
a synthetic rubber made by copolymerizing butadiene with another substance such as acrylonitrile or styrene. [WordNet 1.5]
OXFORD DICTIONARY
buna, n. a synthetic rubber made by polymerization of butadiene.
Etymology
G (as BUTADIENE, natrium sodium)
For further exploring for "buna" in Webster Dictionary Online