A plastic commonly used in injection molding and 3D printing. Most of those plastic parts you have around your house are made of ABS. (Matweb.com)

When two or more parts have to be put together in some way.

The “slop” felt in a mechanical system, typically when the system reverses direction. Parts require clearances to assemble correctly, and these clearances can be felt in moving assemblies. (Wikipedia) [..]

A bearing helps things move. Typically, bearings make it easier for parts to slide or rotate, and to do so for a long time without wearing down. (Wikipedia)

A generic term that describes something that sticks up on a part. An plastic part may require a hole for a screw, so the designer will add a round boss to make room.

Sometimes used as a bearing, a bushing is typically a hollow cylinder used as an interface between a hole and a shaft.

A “cast” part is one that is made by pouring liquid into a mold.