Factors which limit the size of a population no matter how dense the population is are called limiting factors. an example would be.

an example of a limiting factor is competition when all the boys in the yard take all of your girls

Limiting Factors may be physical or biological. The limiting factor also causes competition between individuals of a species population. For example, space is a limiting factor. Many predators and prey need a certain amount of space for survival: food, water, and other biological needs.