antonim

/antonim/

Cases

SingularPluralWhen to use it
nominativeantonimthe antonymantonimlethe antonymsthe plain dictionary form — the doer of the sentence
genitiveantonimnithe antonym'santonimlenithe antonyms'the owner — whose it is
accusativeantonimnithe antonym (as the object)antonimlenithe antonyms (as the object)a specific, known object — whom or what
dativeantonimgeto the antonymantonimlegeto the antonymsdirection or recipient — to where, to whom
locativeantonimdeat / in the antonymantonimledeat / in the antonymswhere it is; also having — mende bar, "I have it"
ablativeantonimdenfrom the antonymantonimledenfrom the antonymswhere 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
myantonimimmy antonymantonimlerimmy antonyms
yourantonimingyour antonymantonimleringyour antonyms
his / herantonimihis / her antonymantonimlerihis / her antonyms
ourantonimibizour antonymantonimleribizour antonyms
you all'santonimigizyou all's antonymantonimlerigizyou all's antonyms
theirantonimleritheir antonymantonimleritheir antonyms

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