What is Brine?

Legal Definition
Brine is a solution of salt (usually sodium chloride) in water. In different contexts, brine may refer to salt solutions ranging from about 3.5% (a typical concentration of seawater, or the lower end of solutions used for brining foods) up to about 26% (a typical saturated solution, depending on temperature). Other levels of concentration are called by different names:

It is held that 0 °F (−18 °C; 255 K) was initially set as the zero point in the Fahrenheit temperature scale, as it was the coldest possible temperature that Daniel G. Fahrenheit could reliably reproduce by freezing brine. By reference, seawater usually freezes at −2 °C (28 °F; 271 K).
-- Wikipedia
Legal Definition
Water saturated or strongly impregnated with salt, seawater or a strong solution of a salt or salts.