I'll be summarizing what's in those two entries, but you should definitely go and read at least the entry on possession for the in-depth explanation, as it's the most common use of this case.
As always, every case has to answer to a question. Genitive answers to " Kā? " which means whose. It can also mean how but since nouns can't easily answer that question, so it doesn't apply.
Often you'll see kāds/kāda or what kind of being answered with a genitive response, even though it's not the question for the case. This is because sometimes genitive nouns are used like adjectives just like in English.
Basically, the genitive is used where we could expect to see " of " or " ' s".
We use the possessive all the time in English - Mary's book or John's house. Latvian works fairly similarly - the possessor will always precede the possessed. (May not be true in poetry.)
What's also neat is that 4th, 5th and 6th singular genitive nouns end in -s , just like in English. No apostrophes here though.
The possessor will always be in the genitive case and the object being possessed will be in the case required by the sentence structure.
Let's look at an example:
Tā ir Marijas grāmata. -- That is Marija's book.
As you can see, tā and grāmata are both nominative. This is because this sentence is a predicate nominative. I think of these type of sentences like an equation. You have a nominative noun on each side with a form of to be in the middle acting as an equals sign. The two nouns are equivalent to each other and the sentence is balanced.
In this example, that is a book or, as an equation: that = book. Whose book? Marija's.
All street names are in genitive. You could think of this as "street of [name]", for example.
Mēs dzīvojam Dzintaru ielā. -- We live on Dzintaru street.
Similarly, anywhere we could conceivably construct a phrase using "of", the genitive is probably the right case for the job, even if you wouldn't ordinarily use it when speaking. This is where the genitive nouns seem to work like adjectives.
Kāda ir jūsu darba adrese? -- What is your work address?
Technically, we could construct this as "What is the address of your work?" So work is in genitive.
As for why kāda instead of kā, it is because, in this case, work is pretty close to being an adjective rather than a noun. [To translate it so it makes sense in English, we use the simpler what as well. This seems to happen a lot with kāds/kāda questions.]
Let's look at what happens when we use the two to ask about the address.
Kāda adrese? Darba. -- What type of address? Work.
Kā adrese? Marijas. -- Whose address? Marija's.
Even though the answers are both in genitive, asking kā or kāda makes a difference in the information you receive back.
One last note on describing an [x] of [y]…
Viņš dzer ābolu sulu. -- He drinks apple juice.
Here again, we could say "the juice of apples" so apple is in genitive. Juice is the direct object of drinks, so it is in the accusative.
As for why apple is in plural in Latvian, unless more information is available, it's assumed to be plural instead of singular. It wouldn't make sense to say ābola sula because then we would be implying that the juice is from only one apple -- the apple's juice. Now, if you juiced one apple for your husband's breakfast, you'd have that knowledge, so that's when you could use the singular. Anything out of a box, however, is definitely plural. (Type of apple, like gala or honeycrisp, does not affect this. The box still contains juice from lots of apples.)
Prepositions taking the Genitive
As you hopefully read in Prepositions, you know that prepositions call one of three cases: accusative , genitive and dative. Since all prepositions take the dative in the plural , we only need to worry about this for singular nouns.
Luckily, of the common Latvian prepositions, only 11 of them take the genitive. (I've listed them at the end of this section.)
The preposition does not decline or conjugate, it will always remain the same. However, the noun that follows it (and is part of the prepositional phrase) must be changed to genitive.
Let's look at how to form a prepositional phrase with no.
Es neesmu no Latvijas. -- _I am not from Latvia. _
No Latvijas is a prepositional phrase. Since no takes the genitive, Latvija must change to Latvijas , the singular genitive form.
Prepositions that take the Genitive
Preposition | Definition
aiz | behind, due to
apakš | below, under
bez | without
kopš | since
no | from, out of
pēc | after, according to
pie | next to, at (the place of)
pirms | since, ago
uz | on
virs | above
zem | below
How to Decline in the Genitive
I love that the genitive ending is the same for every declination in the plural but sometimes the changes in the preceding consonant get me.
The endings are as follows:
vsk. 1. dekl. | 2. dekl. | 2. dekl. exc. | 3. dekl. Kā? -a | -a | -s | -us vsk. 4. dekl. | 5. dekl. | 6. dekl. Kā? -as | -es | -is dsk. 1. dekl. | 2. dekl. | 2. dekl. exc. | 3. dekl. Kā? -u | -u | -u | -u dsk. 4. dekl. | 5. dekl. | 6. dekl Kā? -u | -u | -u Red indicates potential palatalization changes in the preceding consonant.