Ethos Ethos,or the ethical appeal,means to convince an audience of the author's credibility or character. Ethos can be developed by choosing language that is appropriate for the audience and topic (also means choosing proper level of vocabulary),making yourself sound fair or unbiased,introducing your expertise, and by using correct grammar and syntax.Ethos v Ethos, or the ethical appeal, means to convince an audience of the author’s credibility or character. v Ethos can be developed by choosing language that is appropriate for the audience and topic (also means choosing proper level of vocabulary), making yourself sound fair or unbiased, introducing your expertise, and by using correct grammar and syntax