one of a series of rows or ranks rising one behind or above another, as of seats in an amphitheater, boxes in a theater, guns in a man-of-war, or oars in an ancient galley.

one of a number of galleries, as in a theater.

a layer; level; stratum

The wedding cake had six tiers. All three tiers of the firm's management now report to one director.

Australian . a mountain range.

to arrange in tiers.

to rise in tiers.

noun

bank , category , class , course , echelon , file , grade , group , grouping , layer , league , line , order , pigeonhole * , queue , range , rank , row , series , story , stratum , string , column , bracket , level , stack