jer

/dʒer/

Cases

SingularPluralWhen to use it
nominativejerthe earthjerlethe earthsthe plain dictionary form — the doer of the sentence
genitivejernithe earth'sjerlenithe earths'the owner — whose it is
accusativejernithe earth (as the object)jerlenithe earths (as the object)a specific, known object — whom or what
dativejergeto the earthjerlegeto the earthsdirection or recipient — to where, to whom
locativejerdeat / in the earthjerledeat / in the earthswhere it is; also having — mende bar, "I have it"
ablativejerdenfrom the earthjerledenfrom the earthswhere 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
myjerimmy earthjerlerimmy earths
yourjeringyour earthjerleringyour earths
his / herjerihis / her earthjerlerihis / her earths
ourjeribizour earthjerleribizour earths
you all'sjerigizyou all's earthjerlerigizyou all's earths
theirjerleritheir earthjerleritheir earths

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