This is the 2913th most frequent Dutch word.
agressiever
More aggressive.
In this sentence, 'agressiever' is used as a comparative adjective to describe the degree of aggressiveness in someone's response.
Zijn reactie was agressiever dan ik had verwacht.
His response was more aggressive than I had expected.
Here, 'agressiever' illustrates a change in the degree of aggressiveness in the lion's behavior as a reaction to proximity.
De leeuw werd agressiever toen we dichterbij kwamen.
The lion became more aggressive as we approached.
In this instance, 'agressiever' modifies 'toon' to describe the comparative degree of assertiveness or intensity in tone.