Flat Bars: Straight, non-curvbed handlebards as used in traditional bikes
Hybrid: A bike that combines features of two basic types; a road hybrid will have a light frame and the geometry of a road bike, but usually have flat bars
Look: A brand of clipless pedal
MTB: Abbreviation for mountain bike
Skewer: The bar that goes through the front and rear axles to allow quick-release of the wheels
Top Tube: The main tube along the top of the bike frame, also known as the crossbar