A guide who accompanies visitors and sightseers to museums, galleries, etc., and explains matters of archaeological, antiquarian, historic or artistic interest..
A pattern, a way of doing something, especially (now often derogatory) a pattern of thought, a system of beliefs, a conceptual framework.
An example serving as the model for such a pattern.
A set of all forms which contain a common element, especially the set of all inflectional forms of a word or a particular grammatical category.