This is the 2426th most frequent Portuguese word.
assassinado
"Assassinado" means "murdered" in English.
The word 'assassinado' is used here as a past participle of the verb 'assassinar', indicating the action of murder performed on the subject 'ele' (he).
Ele foi assassinado por um desconhecido na noite passada.
He was murdered by a stranger last night.
Here, 'assassinato' is a noun describing the act of murdering someone, used as the subject of the sentence.
O caso de um assassinato é sempre investigado com rigor.
The case of a murder is always investigated with rigor.
In this sentence, 'assassinato' again functions as a noun, referring to the crime being investigated by the detective, and is used as the object of the preposition 'do' (of the).