A level or layer in a structure or system, often used to describe a rank or position in a hierarchy. The company has several tiers of management, each with its own responsibilities.
A row or level of a structure, typically one of a series of rows placed one above the other. The wedding cake was beautifully decorated with three tiers of different flavors.
A group of people or things that are at the same level in a hierarchy. The top tier of athletes in the competition received special recognition.