When your bros leave you out of activities such as lunch, meetings, and basically hanging out. Their activities are the complete opposite of being a bro.
by daigong December 13, 2014
(adj.) 1. An action or event that is unbecoming of a bro. An action or event that a friend would not be a part of or make another suffer through. 2. In the case of an action, there are usually negative effects on others. 3. With an event, the persons involved will likely be miserable throughout said event.
An individual pursues relations with a female that his bro was interested in first. That individual's action of pursuit can be deemed "unbro."
by Double-E July 11, 2009