küpse

/kypse/

Cases

SingularPluralWhen to use it
nominativeküpsethe merchantküpselethe merchantsthe plain dictionary form — the doer of the sentence
genitiveküpsenithe merchant'sküpselenithe merchants'the owner — whose it is
accusativeküpsenithe merchant (as the object)küpselenithe merchants (as the object)a specific, known object — whom or what
dativeküpsegeto the merchantküpselegeto the merchantsdirection or recipient — to where, to whom
locativeküpsedeat / in the merchantküpseledeat / in the merchantswhere it is; also having — mende bar, "I have it"
ablativeküpsedenfrom the merchantküpseledenfrom the merchantswhere 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
myküpsemmy merchantküpselerimmy merchants
yourküpsengyour merchantküpseleringyour merchants
his / herküpsesihis / her merchantküpselerihis / her merchants
ourküpsebizour merchantküpseleribizour merchants
you all'sküpsegizyou all's merchantküpselerigizyou all's merchants
theirküpseleritheir merchantküpseleritheir merchants

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