A generally respectable person who exibits some bro-like characteristics. Such a person may listen to music such as Dave Matthews, Incubus or Jack Johnson. They may dress like a bro with a popped collar and plad shorts or they may use bro phrases like "Chill, lets just chill" or "Lets just kick back with the bros" or "Bro out man this is gonna b awesome" However, a Semi-Bro has the sense to only exhibit one or at most two of these behaviors and still has a chance to be a respected member of soceity. Generally a term of affection for someone that one enjoys the company of and as such the bro habits are amusing rather than frustrating in a Semi-Bro
"Dude lets hook up with Yeates and chill and play some gamecube"
"Wat are you, a bro? Listen to the words coming out of your mouth"
"F*ck you, im not a bro"
"Don't worry bout it man, you've just been hanging out with Jackson too much, your a Semi-Bro at most"