Definition of "tier" []

• One of a series of rows placed one above another: a stadium with four tiers of seats. (noun)
• A rank or class. (noun)
• To arrange (something) into or rise in tiers: tier a wedding cake; balconies that tier upward. (verb-transitive)
• One that ties: a tier of knots. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "These guys operated on what we call a tier one level."
• "We've got a lot of franchisee interest on our business from what I call tier-1 franchisees."
• "There are a few different tiers of security at our school, but most people (teachers and students) have what I refer to as tier one, which is where everything remotely useful is blocked."