Relating to or affecting the abdomen, the part of the body between the chest and pelvis.
From Latin 'abdomen' (belly), possibly from 'abdere' (to hide/conceal), since the abdomen contains and hides internal organs; the adjective form adds '-al' (relating to).
Abdomen might derive from 'to hide' because it's the hidden cavity of the body—medieval anatomists used it to describe the mysterious interior space containing unknown organs.
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