1) The belly piece of a fur skin (OED).
In the Act of 1558 it was said ‘Two pieces called Wombs shall be cut off of every hide to be converted to sole–leather, commonly called Backs. Both the backs and womb shall be brought to fairs and markets to be sold’. The term is on record much earlier: 1377-8 liberantur iij cor ad opus sub celerarii cum v paribus wames per conversum vs xxijd ob, Bolton Priory
c.1425 Item for a dosan wames, drissyng coloryng and shafyng als it is a bouen sayd he shall haf ijd
1465 21 dos’ et 9 wombis coriorum vitulinorum, Hull
1582 for the potinge, pinsing and righting of wambes and rigges [backs] ijs, York
1627 ‘part of any hide from which the sole leather is cut called the woombe, necke, shanke, pole or cheeke’, Beverley.