A name is a noun that is used to refer to an individual object as such, i.e. without classifying it. An onomastic dictionary is a dictionary whose lemmas are names. Normally, an onomastic dictionary does not treat just any kind of name of the language, but one class of names. The following classes of names commonly have dictionaries to them:

• first names (anthroponyms)
• family names
• place names (toponyms)
• waters (hydronyms)
• mountains (oreonyms)

Since names do not have meaning in the sense that common nouns have meaning, the purpose of a name dictionary differs from that of a general dictionary, and its microstructure differs accordingly. Commonly, the entry provides the following kinds of information:

• the lemma in a “citation form”, which may be the one closest to its etymological origin or the one most frequently found,
• the region where the name is found frequently or where it originates,
• variant (phonological, orthographic, phonological) forms of the lemma, each with diatopic, diastratic or diachronic marking or even details on written documentation,
• the etymology (language of origin, original word formation, original meaning) of the name.

Answering the interests of laymen and specialists alike, etymology plays a prominent role in onomastic dictionaries, and to that extent they are almost a subtype of the etymological dictionary.