Frozen mass (4)
(Other definitions for floe that I've seen before include "Comparatively small piece of floating ice" , "Frozen piece of Arctic" , "Floating flat mass of ice" , "Piece of ice at sea" , "Broken piece of pack-ice" .)
(Other definitions for iceberg that I've seen before include "main danger" , "Kind of lettuce" , "Calf's parent" , "Floating shipping hazard" , "Type of crisp lettuce" .)