NOUN (1)

1. a large two-handed saw formerly used to cut logs into planks; one man stood above the log and the other in a pit below;

The Collaborative International Dictionary of English v.0.48:

pitsaw \pit"saw\ n.
   A large two-handed saw formerly used to cut logs into planks;
   one man stood above the log and the other in a pit below.
   [WordNet 1.5]