When Is A Bridge Not A Bridge?

In creating my "Bridges" gallery, I came across a small conundrum. I have one shot of a pier at Springmaid Beach in South Carolina. The shot seems obvious to go into my gallery, but my hunch was that it did not fit any technical definition of a bridge. So I hit Google and found i was right --

"A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle."

Words evidently mean things. I also used to use the word trestle to mean a bridge for railroads, but apparently that was wrong, too. A trestle is evidently the frame of the bridge. So Now I'm confused. I've tried to stop using the term trestle, but will include my pier shot in my bridges gallery.