This is the 15300th most frequent German word.
unsre
"Unsre" is an informal or poetic contraction of "unsere," meaning "our" in English.
The word "unsre" (shortened form of "unsere") is a possessive pronoun indicating ownership or relationship, and here it modifies the noun "Katze" (cat).
Unsere Katze schläft den ganzen Tag.
Our cat sleeps all day.
The word "unsre" specifies whose joy is being referred to; here, it signifies possession or association with the speakers.
Unsre Freude war unermesslich.
Our joy was immense.
The word "unsre" (short form of "unsere") shows possession, referring to the friends associated with the speakers.