Z: So we've got two meaning for this word a remark made in order to anger, wound, or provoke someone.provoke or challenge (someone) with insulting remarks.

　　M: 有两种解释哈，第一种就是激怒，使某人生气。 第二种就是用一些带有侮辱性的话来挑战别人。

　　rant

　　M: Does the word has the same meaning with "complain"?

　　Z: Not exactly, the verb definition is speak or shout at length in a wild, impassioned way

　　you can complain while ranting.

　　wild 野蛮的，impassioned 激烈的

　　roast

　　M: Can we use that word to make fun of someone?

　　Z: Not so much to make fun of people, since it means to criticize or reprimand severely.

　　criticize 批评 reprimand 训斥

　　let off steam 宣泄

　　get something off one's chest 把...倾吐出来