Question

define rancidity and its uses

Answer 1

When foods containing oil and fats get oxidized they become rancid. Their taste and odour changes

Answer 2

mate rancidity means the oxidation of oily foods due to which it starts giving a foul smell and also the taste changes. I don't think that there are uses of rancidity but rancidity occurs in the food containing oil and stuff when come in contact with air will oxidise and give foul smell.