gir

/ɡir/

Cases

SingularPluralWhen to use it
nominativegirthe weightgirlethe weightsthe plain dictionary form — the doer of the sentence
genitivegirnithe weight'sgirlenithe weights'the owner — whose it is
accusativegirnithe weight (as the object)girlenithe weights (as the object)a specific, known object — whom or what
dativegirgeto the weightgirlegeto the weightsdirection or recipient — to where, to whom
locativegirdeat / in the weightgirledeat / in the weightswhere it is; also having — mende bar, "I have it"
ablativegirdenfrom the weightgirledenfrom the weightswhere 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
mygirimmy weightgirlerimmy weights
yourgiringyour weightgirleringyour weights
his / hergirihis / her weightgirlerihis / her weights
ourgiribizour weightgirleribizour weights
you all'sgirigizyou all's weightgirlerigizyou all's weights
theirgirleritheir weightgirleritheir weights

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