Not brotherly; not befitting a brother.(adjective)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "unbrotherly" in a sentence
"For example, Professor Scudder argued that "the Church, like her Master, is in a way more concerned over the spiritual state of the prosperous than over that of the poor," because the rich "countenance unbrotherly things.""
""You leave me no choice, since my brother uses me unbrotherly.""
"See, here is the scroll, coldly worded, but far less unkindly than his unbrotherly message by Ital"