The term procedural is usually used to refer to either procedural programming, procedural generation (media related) or law procedures.
The term procedural programming is derived from structured programming and is often referred to as imperative programming. The basic concept is a set of procedures which are called in a specific order, this order referred to as a routine. Different methods or functions are put together to create a procedure which can be called at any time during the programs execution. Two popular examples of procedural programming would be the Linux Kernal (Git) and Apache HTTP web server.
Procedural generation is a very common term in the media business. It refers to content which is generated using set algorithms rather than being manually created. This usually means creating content on the fly rather than the traditional method of generating it prior to being distributed. A perfect example would be in computer games and level design software for video games.
Procedural law refers to a set of rules set by a court. These rules determine how a civil or criminal lawsuit should be handled within the court. The rules are meant to set a fair and consistent playing field to ensure due process is given to each case.