noun
block
BLAHK/blɑːk/
A solid or bounded section treated as one unit.
A solid wooden block shows clear grain along its flat sides.

Etymology
Old French bloc named a solid piece of wood, later generalized to other materials. The city sense developed through a “compact mass” of buildings, then an area enclosed by streets.
In context
When starting a new design, a Part Design is like focusing entirely on a single block. You’re not building a castle yet; you’re just defining the height