Definition of old skool:
(adj) :
(music, eye dialect, slang) Alternative spelling of old school (“of or relating to hip-hop or rap music of the late 1970s and 1980s (or more recent music of this style) as contrasted with newer styles of such music”). [Now often old-school: characteristic of a method for accomplishing a task, a style, or a way of thinking that was employed in a former era, remembered either for its inferiority to the current method, or for its superiority over the new way.]
(n) :
(music, eye dialect, slang) Alternative spelling of old school (“hip-hop or rap music of the late 1970s and 1980s (or more recent music of this style) as contrasted with newer styles of such music”). [Preceded by the: a group of people characterized by being conservative or traditional; also, a method for accomplishing a task, a style, or a way of thinking that was employed in a former era, remembered either for its inferiority to the current method, or for its superiority over the new way.]