The phrase "desperate need" refers to a situation where there is an urgent and critical requirement for something, often due to lack or scarcity. It suggests that the thing needed is essential for survival, well-being, or success, and without it, things could become very difficult or even impossible. The term can be used in various contexts such as a person's need for food, water, shelter, medical care, education, financial assistance, etc., depending on the circumstances they are facing. In summary, "desperate need" implies that something is vitally important and must be addressed immediately to prevent further harm or hardship.