Webster Dictionary

1. Tubbing(u)

   of Tub

2. Tubbing(noun)

   the forming of a tub; also, collectively, materials for tubs

3. Tubbing(noun)

   a lining of timber or metal around the shaft of a mine; especially, a series of cast-iron cylinders bolted together, used to enable those who sink a shaft to penetrate quicksand, water, etc., with safety