This is the 10604th most frequent Turkish word.
bıçaklayan
"Stabber" or "someone who stabs."
Here, 'bıçaklayan' functions as a participle modifying 'saldırgan', describing the attacker as 'the one who stabs'.
Adam kardeşini bıçaklayan saldırganı durdurdu.
The man stopped the attacker who stabbed his brother.
In this sentence, 'bıçaklayan' is used as a participle to describe 'kişi', explaining the action carried out.
Köpeği bıçaklayan kişi polis tarafından yakalandı.
The person who stabbed the dog was caught by the police.
Here, 'bıçaklayan' is used as a verb participle in conjunction with 'birini', referring to the act of stabbing.