ice shelf

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A body of glacial ice that extends out from a coastline and that floats, at least in part, rather than resting on the sea floor.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A thick, floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface. Ice shelves are found in Antarctica, Greenland, and Canada only.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun ice that is attached to land but projects out to sea