bu·na rubber 
(bnə, by-)
(bnə, by-)n.
Any of a family of synthetic rubbers made from the polymerization of butadiene with a sodium catalyst. Copolymers including styrene or acrylonitrile are the most common members of this group.
[From Buna, former trademark for such rubber.]
- Four-H Club
- Four Horsemen of the Apocalypse
- Four Hundred
- Fourier
- Fourier analysis
- Fourierism
- Fourierist
- Fourierite
- Fourier series
- Fourier transform
- four-in-hand
- four-leaf clover
- four-letter word
- four-o'clock
- four-peat
- fourpenny nail
- fourplex
- four-poster
- fourragère
- fourscore
- foursome
- foursquare
- foursquarely
- four-star
- fourteen