The Quenya genitive is formed with the suffix -o and is roughly equivalent to the English preposition “of”. Tolkien talked about the circumstances in which the genitive would be used at some length in his Quenya and Eldar essay written in 1960s, mostly comparing it to the possessive case (WJ/368-369):
Quenya
Quenya Grammar P24: Dative
The Quenya dative is used for the indirect object of a phrase and is formed using the suffix -n. The indirect object is the recipient or beneficiary of an action, as opposed to the direct object which is the immediate target. In English, the indirect object comes immediately before the
Quenya Grammar P23: Accusative
The accusative form in Quenya is used for the object of verbs and is unmarked in “modern” Quenya (Tarquesta). According to the Plotz letter, there was a distinct accusative form in Classical Quenya (Parmaquesta), marked with a long final vowel in the singular, and by the use of an -i
Quenya Grammar P22: Nominative
The nominative form in Quenya is used for subject of a sentence and is unmarked. It is simply the base form of the noun if singular, or its simple dual, plural or partitive plural forms if non-singular. The verb must be inflected into either the dual or plural to agree
Quenya Grammar P21: Nouns Cases
For Quenya as Tolkien conceived of it in the 1950s and 60s (Late Quenya), the language has seven major noun case inflections: The dative case used for the indirect object of a sentence. The genitive case that was more or less equivalent to English “of”. The possessive-adjectival case, mostly used
Quenya Grammar P20: Plural Nouns
Like most languages, Quenya distinguishes between singular (one) and plural (multiple) nouns. Quenya has two special plural forms, the dual (for pairs) and the partitive plural (for portions of groups = “some”). This entry discusses the general plural, which is used for all the other forms of noun plurality. Quenya
Quenya Grammar P19: Partitive Plural
In addition to the “general” plural, Quenya has a special “partitive” plural used when describing a portion of a group. The partitive plural is formed using the suffix -li, variously translated as “some, many, a lot of” (PE17/62, 127, 135; VT47/12). It is derived from the primitive root √LI “many”
Quenya Grammar P18: Dual Nouns
The Quenya dual form is a special plural used for when there are exactly two of the items in question: atanu “two men”, lasset “both leaves”. It can be translated as “two”, “both” or “(the) pair of”. It is used most frequently with items that are a “natural pair”, such
Quenya Grammar P17: Declension for Number
Like English, Quenya has singular and plural nouns, with singular unmarked and plural marked by -i or -r. However, Quenya has two additional “special plurals”, the dual used when there are only two of an item (“both”), and the partitive-plural when the plural represent a subset of a larger group
Quenya Grammar P10: Definite Article
Quenya has a definite article i that is more or less equivalent to English “the”: i atan = “the man” [human]. Like English, the definite article is used to specify a definite thing specifically referred to (“the man”), as opposed to an indefinite thing (“a man”). Unlike English, there is