Swedish nouns are divided into declensions depending on their stem, how the plural is formed, and on their gender (which is either 'uter' or 'neuter'). Within these declensions, they are inflected according to:
Number: singular or plural.
Definiteness: definite or indefinite.
Case: nominative or genitive. (In Old Swedish, also accusative and dative, which has survived in a few standard phrases.)
Inflection by case is rather trivial: the genitive is the nominative with an "s" suffixed, if the word doesn't already end in an "s" sound, in which case nothing (or, optionally, an apostrope) is added. A few words and names borrowed from Latin have latin genitives, although it is possible to ignore this and treat them like other words.
There are essentially five declensions:
First declension, plural indefinite on -or.
There are two groups of words within this declension, those that have a singular indefinite suffix -a, and those that use the bare stem. The words with an -a suffix in the singular indefinite uses -an to make the singular definite. The other words use -en. All words in this declension are uter.
Second declension, plural indefinite on -ar.
Like the first declension, the second also has two primary groups of words; those that add -e in singular indefinite, and those which use the bare stem. The singular definite has an -en suffix. All words in this declension are uter.
Third declension, plural indefinite on -(e)r.
Words of this declension always use the bare stem for the singular indefinite, and add -(e)n or -(e)t in the singular definite. There are both neuter and uter words in this declension.
Fourth declension, plural indefinite on -(e)n.
Singular indefinite: bare stem. Singular definite: -(e)t. There are only neuter words in this declension.
Fifth declension. Plural indefinite: bare stem.
Singular indefinite: bare stem. Singular definite: -(e)t or -(e)n. There are both neuter and uter words in this declension.
All nouns, except neuters of the fifth declension and some irregular words, add -na to the indefinite plural to form the definite plural. But words with a plural already ending in "n" do not usually double this "n" except in special cases, most of which concern words that are irregular for other reasons, too.
Fifth-declension neuters have definite plurals on -en.
Inflection paradigm for the five declensions:
1st 2nd 3rd 4th 5th
sg.indef. flaska buske minut vittne brev
sg.def. flaskan busken minuten vittnet brevet
pl.indef. flaskor buskar minuter vittnen brev
pl.def. flaskorna buskarna minuterna vittnena breven
English: bottle bush, shrub minute witness letter (`mail')
The gender can easily be determined by looking at the singular definite form of the word (which always end in either "n" or "t"); the words with a singular definite on "n" are uter, and others are neuter.
In the third and fourth declension, there are a number of words that end in -er and -el; these usually drop the `e' before the final consonant when an added inflection suffix begins with a vowel. E.g. en konstapel (3u, constable), pl. konstaplar, and ett papper (4n, paper), sg.def. pappret. However, in the sg.def. case in the third declension, the suffix is instead usually reduced from -en to -n, e.g. konstapeln. Forms such as konstaplen are possible, but often sound strange or archaic.
The third declension contains some neuter words, in which case the sg.def. form above ends in -et instead of -en. One example is parti, a word with several barely related meanings, inflected thus: parti, partiet, partier, partierna. (Two meanings of the word are (1) `party' in the sense of a grouping of people, such as a political party or a `side' in a legal dispute, and (2) a `game' in the sense of the occasion of playing it from start to finish, e.g. `ett parti schack' = a game of chess.)
Wan't that fun? Thanks to the Lysator project for the text.
(not)... heh..