What is the term used for "not getting enough" of something?

The term "deficiency" refers to a lack or insufficient quantity of something that is necessary or desired. In various contexts, such as nutrition or resources, a deficiency highlights the absence or shortage of an essential element, leading to potential negative outcomes. For instance, a nutrient deficiency can result in health issues due to the body not receiving adequate vitamins or minerals it requires to function optimally.

In contrast, a surplus indicates having more than enough of something, while excess suggests an overabundance that can also lead to negative consequences. A shortage refers to a situation where demand exceeds supply, but it is not specifically limited to the concept of not having enough of a necessary component, making "deficiency" the most appropriate term in this scenario.