This is just a short introduction to onomastics in English for non-specialists. Some scholars (onomasticians) might want to express these ideas differently, or maybe disagree with some altogether. But I think most of the scholars who do it will agree with most of them. The main point here is to get you interested and to want to know more about what we do!
Onomastics is the study of proper names, from the Greek word onoma, `name'. Proper names are a very important part of our lives. We all have personal proper names, and we live in streets and towns with their own proper names. Our pets may have proper names, as may any spiritual beings we believe in. We may change our names at important points in our lives. We may spend ages deciding what proper name, or how many, to give our babies. Names can be hugely culturally and politically important. It makes a difference whether you live in Montreal or Montréal. What is the truth behind these wonderful things?
The most important thing about a proper name is that when a speaker or writer uses it, s/he picks out a single entity but, in doing so, does not make direct use of the senses of any words which appear to make it up. Many names are obscure in any case - they don't consist of words that we can interpret as they stand (like Warsaw or Neptune). So proper names are, or have become, meaningless, or at least they don't "mean" in the way that ordinary words mean. If a name appears to consist of ordinary words, there may be a problem in equating what it apparently means with what it can refer to.
A favourite example for this writer is the place-name County Oak in England. It was the name of an oak-tree which stood on a county boundary. The oak is dead and gone; the boundary has moved. But the name is still alive as the name of a community that has grown up near where the original tree was. So when the name County Oak is used, the speaker does not directly use the meanings of either of the two words, which are still ordinary words of English, and nor does s/he refer to the thing that the name originally denoted.
This makes names different from expressions in ordinary language. In normal usage, you can't use the phrase 'the old oak-tree' without relying on the meanings of 'the,' 'old,' 'oak', and 'tree,' and without respecting the rules of grammar which combine them. And such normal phrases can apply to every entity which satisfies the description made by the words, not to just one single entity. (Some phrases may become idioms, like a 'can of worms', which has nothing to do with cans or worms in everyday chat--it means `a situation or event likely to cause more problems', but not having a regular normal meaning does not make all idioms into proper names. A can of worms still obviously has a general meaning which doesn't apply to only a single entity.)
What onomasticians do
Onomasticians analyse proper names in various ways. They may study:
(1) the history of individual names or of the names found in particular social groups or areas, to discover their original meanings and establish their social or geographical distributional patterns (2) the linguistic devices that are used to create names and keep them in circulation, in association with the language or languages of the community that uses them (3) current patterns and processes of naming, to establish the distribution and popularity of particular names or name-types (4) the connotations of names, e.g. how, or whether, personal names relate to personality or are subject to changes in fashion (5) how different names may apply to the same entity, even in the same culture, e.g. in pet-naming or nicknaming (6) how ordinary words and phrases may become proper names, and vice versa, and/or how they may be used metaphorically or become associated with entities which are not the original thing named (like County Oak above) (7) the practical problems created by the fact that names are used across linguistic boundaries and that different names may apply to the same entity; for place-names, for example, onomasticians may suggest international and standard usages, and resolve disputes about them (8) the naming of persons, places, etc. in second-order worlds such as myth, literature and film, and in supernatural worlds (9) what proper names in general are and what they do (how they are used), in order to refine our understanding of their nature