The case form of the first part of a compound

Possible cases

The first part of a closed compound is usually in the nominative case or in the genitive case. Instead of the nominative, a special compositive form is used, if the word has such a form. The rules for nominative vs. genitive case are described in the next subsection.

Any other case form, except the comitative, may appear, too. However, they are normally used only when the second part names an action and the first part consists describes the location or other properties of the action, e.g. työssäoppiminen, also written työssä oppiminen (learning at work).

Nominative vs. genitive

The first part of a closed compound is in the genitive when some of the following conditions is met:

• The first part expresses the object of the action expressed by the second part, e.g. tienrakennus (road construction, from tie “road” and rakennus “construction, building”) and kaupanpurku (annulment of a sale).
• The first part expresses the agent of the action expressed by the second part, e.g. linnunlaulu (bird song, from lintu “bird” and laulu “song, singing”). This is relatively rare, because usually open compounds (linnun laulu or, with plural, lintujen laulu) are used instead.
• The first part specifies a context to which the second part belongs, e.g. tienpinta (surface of the road; pinta means “surface”).
• The first part otherwise specifies who or what possesses (concretely or abstractly) the thing expressed by the second part. For example, kansanedustaja (member of parliament) has the word kansa (people) in the genitive, since the compound means “representative of the people”. Compare this with kauppaedustaja (trade representative), which has has kauppa (trade, sale) in the nominative, since it is not a matter of representing trade but rather representing a company in trade.

Otherwise, the nominative or the compositive form is used, as a rule. The nominative indicates that the first part determines the second part in some other way than those described above. For example, in kirjakauppa (book shop) it tells what the shop sells, and in alkupalkka (starting salary, literally: start salary) it tells what situation the salary applies to.

However, there are many exceptions, especially in old vocabulary. Moreover, it is often difficult so say how an expression should be analyzed. The nominative might be used when there is no compelling need to use the genitive.

If the first part is in the nominative, it is always in singular—even when the word is otherwise used in plural only, e.g. hääkutsu “wedding invitation”, even though we otherwise use häät (wedding) in plural.

If the first part is in the genitive, it is usually in singular, even when meaning is plural, e.g. sairaanhoitaja (nurse; literally: sick’s caretaker). In some terms, there is variation, e.g. viruksentorjunta ∼ virustentorjunta (virus protection).