bed, bottom - a depression forming the ground under a body of water; "he searched for treasure on the ocean bed" --3is a kind ofnatural depression, depression --3has particulars:
seam, bed - a stratum of ore or coal thick enough to be mined with profit; "he worked in the coal beds" --5is a kind ofstratum --5has particulars: coal seam
layer, bed - single thickness of usually some homogeneous substance; "slices of hard-boiled egg on a bed of spinach" --6is a kind ofsheet, flat solid --6is a part of laminate --6has particulars: