A vegetable oil produced from the seeds of the Jatropha curcas, a plant that can grow in marginal lands and common lands.  When jatropha seeds are crushed, the resulting jatropha oil can be processed to produce a high-quality biodiesel that can be used in a standard diesel car, while the residue can also be processed and used as biomass feedstock to power electricity plants or used as fertilizer (it contains nitrogen, phosphorous and potassium).  The plant may yield more than four times as much fuel per hectare as soybean, and more than ten times that of corn. A hectare of jatropha has been claimed to produce 1,892 litres of fuel. However, as it has not yet been domesticated or improved by plant breeders, yields are variable.
(Thanks to Biofuel Digest for this definition)