sırt

/ sɯrt /

Cases

SingularPluralWhen to use it
nominative sırt the back sırtla the backs the plain dictionary form — the doer of the sentence
genitive sırtnı the back's sırtlanı the backs' the owner — whose it is
accusative sırtnı the back (as the object) sırtlanı the backs (as the object) a specific, known object — whom or what
dative sırtha to the back sırtlağa to the backs direction or recipient — to where, to whom
locative sırtda at / in the back sırtlada at / in the backs where it is; also having — mende bar, "I have it"
ablative sırtdan from the back sırtladan from the backs 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
my sırtım my back sırtlarım my backs
your sırtıŋ your back sırtlarıŋ your backs
his / her sırtı his / her back sırtları his / her backs
our sırtıbız our back sırtlarıbız our backs
you all's sırtığız you all's back sırtlarığız you all's backs
their sırtları their back sırtları their backs

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