The crossword solution for the term 'SOURCE OF A NUTRITIOUS OIL' is COD, which stands for codfish. Codfish are a type of fish found in the North Atlantic and Pacific oceans. They are a popular source of food and are known for their high levels of omega-3 fatty acids, which are beneficial for human health. Codfish oil is extracted from the livers of codfish and is used as a dietary supplement due to its high levels of nutrients.