This is the 15742nd most frequent German word.
zutraulichen
"Zutraulichen" means "trustful" or "confiding."
The word 'zutraulich' here describes the characteristic of the cat being friendly and trusting in nature.
Die Katze ist sehr zutraulich geworden.
The cat has become very trustful.
In this sentence, 'zutraulich' modifies the word 'Verhalten' (behavior) to describe its nature as being trustful and friendly.
Dieses zutrauliche Verhalten des Pferdes überrascht mich.
This trusting behavior of the horse surprises me.
Here, 'zutraulich' is used to depict the dogs' characteristic of being accommodating and approachable.