otdel

/otdel/

Cases

SingularPluralWhen to use it
nominativeotdelthe departmentotdellethe departmentsthe plain dictionary form — the doer of the sentence
genitiveotdelnithe department'sotdellenithe departments'the owner — whose it is
accusativeotdelnithe department (as the object)otdellenithe departments (as the object)a specific, known object — whom or what
dativeotdelgeto the departmentotdellegeto the departmentsdirection or recipient — to where, to whom
locativeotdeldeat / in the departmentotdelledeat / in the departmentswhere it is; also having — mende bar, "I have it"
ablativeotdeldenfrom the departmentotdelledenfrom the departmentswhere 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
myotdelimmy departmentotdellerimmy departments
yourotdelingyour departmentotdelleringyour departments
his / herotdelihis / her departmentotdellerihis / her departments
ourotdelibizour departmentotdelleribizour departments
you all'sotdeligizyou all's departmentotdellerigizyou all's departments
theirotdelleritheir departmentotdelleritheir departments

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