What does Bt stand for in Bt Brinjal?

Bt stands for bacillus thuringiensis, a common soil bacterium toxic to lepidopteran insects. When "Bt" is placed before a plant name, such as in "Bt Brinjal" (the brinjal is known in the US as eggplant), it means the plant has been genetically modified to produce a protein toxic to certain insects in the same way the bacteria does.

The protein has not been shown to be harmful to humans but is controversial in other contexts.