Dependency is defined as a state of needing something or someone.
(noun)When you rely on coffee to get you through the day, this is an example of a caffeine dependency.
See dependency in Webster's New World College Dictionary
noun pl. dependencies
See dependency in American Heritage Dictionary 4
also de·pen·dan·cy
noun pl. de·pen·den·cies also de·pen·dan·ciesLearn more about dependency