A tuple is a fixed fixed-length list containing elements that need not have the same type. It can be, and often is, used as a key-value pair. A row (sometimes called a record) is the set of fields within a table that are relevant to a specific entity.
The stem wall on a concrete foundation is essentially the supporting wall that joins the foundation of a building to the vertical walls of the structure that is constructed atop the foundation.
A crawlspace foundation is where the home is supported off of the ground level by approximately 2 feet. Stem walls extend from the footings around the perimeter of the foundation to support the home. Often times an alternative is used instead of the stem wall. This is called pier and beam.