pier

n. 1 a structure built out into the sea, a lake, etc., as a promenade and landing-stage. B breakwater. 2 a support of an arch or of the span of a bridge; pillar. B solid masonry between windows etc. [latin pera]

n. Any detached mass of masonry, whether insulated or supporting one side of an arch or lintel, as of a bridge; the piece of wall between two openings.