ALL meanings of borax pentahydrate
bo·rax pen·ta·hy·drate
B b - noun borax pentahydrate a white, crystalline, water-soluble solid, Na 2 B 4 O 7 ⋅5H 2 O, used chiefly for killing weeds, as a water softener, and as a disinfectant and deodorizing agent. 1