preparatory work; groundwork; subcontract work
Refers to the preliminary or less-skilled work that supports a main task, often in construction or manufacturing. Can also mean work done under a subcontract.
As preparatory work for the carpenter, I cut the materials in advance.
We subcontract the machining of these parts as groundwork.
Compound of 下 (した, 'under, lower') and 仕事 (しごと, 'work'), literally 'under-work' or 'lower work'.