The guiding beliefs of a person, group, or organization
In my words: Ethos is when someone is going with their morals like the right and the wrong and when there persuading someone to do something.
Ethos in Romeo and Juliet
Ethos is used in Romeo and Juliet when Romeo wants to kill himself with a highly lethal poison, even deadly to speak of.
In Romeo and Juliet, Romeo says 'Let me have a dram poison, such soon speeding gear as will disperses itself through all veins' ( Shakespeare V,1,64 ) Romeo is saying let this poison take him quick. Romeo wants to die quickly so he can be with juliet. The reason behind taking his own life is that he does not want to live without Juliet, his love of his life.
Another form of ethos is when the The Apothecary Says "Such mortal drugs i have ;but Mantua's law is death to anyone who utters them. ( Shakespeare V, 1 66 )
The apothecary is saying that that he has a deadly drug that will kill anyone quickly who consumes it. It's so deadly that if even spoken of you will die. The reason of death if you speak of it is because this poison is lethal it's against the law. These are some examples of ethos in Romeo and Juliet.