Question

Define the term Rancidity.​

Answer 1

Rancidification is the process of complete or incomplete oxidation or hydrolysis of fats and oils when exposed to air, light, or moisture or by bacterial action, resulting in unpleasant taste and odor. 

Answer 2

it's rain-acidity not rancidity, anyway, when rain falls with the mixture of oxide of sulphur and nitrogen, it forms acid rain