biy

/bij/

Cases

SingularPluralWhen to use it
nominativebiythe princebiylethe princesthe plain dictionary form — the doer of the sentence
genitivebiynithe prince'sbiylenithe princes'the owner — whose it is
accusativebiynithe prince (as the object)biylenithe princes (as the object)a specific, known object — whom or what
dativebiygeto the princebiylegeto the princesdirection or recipient — to where, to whom
locativebiydeat / in the princebiyledeat / in the princeswhere it is; also having — mende bar, "I have it"
ablativebiydenfrom the princebiyledenfrom the princeswhere it comes from; also "than" when comparing
When to use each case
nominative
the plain dictionary form — the doer of the sentence
genitive
the owner — whose it is
accusative
a specific, known object — whom or what
dative
direction or recipient — to where, to whom
locative
where it is; also having — mende bar, "I have it"
ablative
where it comes from; also "than" when comparing

The endings are the same ones the pronouns wear — that page explains when each case is used.

With an owner

One ownedSeveral owned
mybiyimmy princebiylerimmy princes
yourbiyingyour princebiyleringyour princes
his / herbiyihis / her princebiylerihis / her princes
ourbiyibizour princebiyleribizour princes
you all'sbiyigizyou all's princebiylerigizyou all's princes
theirbiyleritheir princebiyleritheir princes

The overlap in the last rows is real, not a mistake: biyleri can mean "his / her princes", "their prince", or "their princes" — context decides.