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 stem caster is an assembly containing a wheel or set of wheels mounted onto a fork, with a stem for attaching it to the bottom of an object. They are usually found in sets of four and are used to provide mobility to an otherwise stationary item. A stem caster can be either rigid or swivel.