The definition and original answer is the origin of the concept, in Design patterns. This book deals with the concept at a very theortical level, rather than the management speak that has infiltrated the area. Their view is that design patterns are just names for common idioms; they enumerate some and justify their positions.
They avoid the "What design pattern should I use" type of question, instead dealing with problem as "Am I naturally stepping into a well known area? If so, can others experience help me?". Design patterns, to me, are not like prefab components you glue together to make a solution. They are just guidance repositories for when you come across a situation similar to one others have countered, and give names to allow people to refer to the general situations in conversation.
