Rebar, steel rebar, deformed steel bar, twisted steel bar, iron rods for concrete construction, construction steel rebar Definition: Rebar, common known as steel reinforcing bar, is usually applied to reinforced concrete and reinforced masonry structures. Formed from mild steel, it is given ribs for better frictional adhesion to the concrete. In other words, rebar is an iron rod, a weldable plain reinforcing steel bar, which can be also used for