Is Tagesordnung der, die or das?

The correct German article for Tagesordnung is die. The noun Tagesordnung is Feminine. So you always say: die Tagesordnung. Learn the article together with the noun — German nouns don't follow predictable gender rules most of the time.

The plural of Tagesordnung is: die Tagesordnungen. In the plural, every German noun takes the article "die". So: die Tagesordnungen. Example: ein Tagesordnung → zwei Tagesordnungen.

Correct: die Tagesordnungen. The form "die Tagesordnungs" is wrong. The plural of die Tagesordnung is die Tagesordnungen. In the nominative plural, you always use the article "die".

die Tagesordnung follows the four German cases. Nominative: die Tagesordnung, Accusative: die Tagesordnung, Dative: der Tagesordnung, Genitive: der Tagesordnung. In plural: die Tagesordnungen / den Tagesordnungen. Learn these forms together with the noun.

The genitive singular of die Tagesordnung is: der Tagesordnung. The genitive plural is der Tagesordnungen. German uses the genitive to express possession or belonging. Example: die Farbe der Tagesordnung.

The dative plural of Tagesordnung is: den Tagesordnungen. In German, dative plural nouns usually end in "-n". So you say: "mit den Tagesordnungen". Use this case after prepositions like mit, von, bei, zu.

Tagesordnung ends in -ung. German nouns with this ending are almost always feminine. Nouns ending in -ung are almost always feminine (die). That's why the article for Tagesordnung is die.

Tagesordnung is a noun and must be capitalized in German. You'll find example sentences above for each case. The article die stays the same in nominative singular but changes in other cases. Practice declension in your own sentences.

Yes, Tagesordnung is a noun (also called a substantive). German nouns are always capitalized. The article for Tagesordnung is die. Every German noun has a fixed article you must memorize.