Definitions
1.NounA raised platform built from the shore out over water, supported on piles; used to secure, or provide access to shipping; a jetty."Your boat is docked at the pier."
2.NounA similar structure, especially at a seaside resort, used to provide entertainment."There is a gaming arcade on the pier."
3.NounA structure supporting the junction between two spans of a bridge.
4.NounA rectangular pillar, or similar structure, that supports an arch, wall or roof, or the hinges of a gate.
5.NounA long corridor-like structure with multiple gates extending from an airport terminal.