One tier or layer above another; a storey of a house. Now only dialect.

A layer, stage, stratum. Also transferred of the lateral branches of trees at varying heights. Obsolete.

A row, rank, range, course; usually one of a series of rows placed one above another, or at least rising each above the preceding one; e.g. tiers of…

Any of a number of rows or lines of things placed at different heights; a level, tier. Now rare.

figurative and in extended use. Something compared to a storey of a building; each of a series of stages or divisions lying horizontally one above…

transferred. Something resembling a step; each of a series of things placed one above another like steps; row, tier, shelf, etc.