when two guys have a very close bond, to the point where they act like a couple, except that they are both straight. Signs of a bromance include, but are not limited to: knowing what the other is thinking, hanging out 27/7, hugging, extensive high-fiving, and sharing clothes. Some famous examples include Sherlock Holmes and Watson, and Captain Kirk and Spock.
You never see one of those guys without the other. They have such an epic bromance!