means The line where a body of water meets the land, marking the edge of a coast, lake, or sea.

from A transparent English compound of "shore" + "line." "Shore" is the old word, related to Middle Low German and Dutch terms like "schore," and possibly tied to the notion of land "shorn" or cut off by the water's edge. "Line" descends from Latin "linea," a flaxen thread, the same root that gives us a drawn line. So a shoreline is, quite literally, the thread where shore is drawn — though, as the sea keeps reminding us, it's a line written in sand and constantly redrafted.