pier

noun

1. a structure built on posts extending from land out over water, used as a landing place for ships, an entertainment area, a strolling place, etc.; jetty.
2. (in a bridge or the like) a support for the ends of adjacent spans.
3. a square pillar.
4. a portion of wall between doors, windows, etc.
5. a pillar or post on which a gate or door is hung.
6. a support of masonry, steel, or the like for sustaining vertical pressure.
7. a long passageway or corridor that extends from a central area of a building, especially one at an airport that leads to boarding gates.

noun

1. a structure with a deck that is built out over water, and used as a landing place, promenade, etc
2. a pillar that bears heavy loads, esp one of rectangular cross section
3. the part of a wall between two adjacent openings
4. another name for buttress (def. 1)

n.mid-12c., “support of a span of a bridge,” from Medieval Latin pera, of unknown origin, perhaps from Old North French pire “a breakwater,” from Vulgar Latin *petricus, from Latin petra “rock” (see petrous), but OED is against this. Meaning “solid structure in a harbor, used as a landing place for vessels,” is attested from mid-15c.