This is the 7425th most frequent Catalan word.
assetjar
To besiege; to harass.
The word 'assetjar' here means to besiege, as in surrounding a fortress or locale during a military operation.
Els soldats van assetjar el castell fins que el van conquerir.
The soldiers laid siege to the castle until they conquered it.
The word 'assetjar' in this sentence refers to harassment, usually through persistent or irritating actions directed at someone.
Alguns usuaris d'internet han denunciat sentir-se assetjats per missatges anònims.
Some internet users have reported feeling harassed by anonymous messages.
While 'assetjament' is a noun form, it's closely related to 'assetjar', denoting harassment or bullying activities.