It’s not very exciting, but it’s all too necessary. This odd little word came from shortening and combing the words “reinforcing bar.” What are these heavily ridged steel rods reinforcing exactly” Concrete for columns, beams, floors, heavy-duty walls, pathways, bridges, etc. (They are the spindly, often slightly rusted metal pieces you see sticking out of concrete during construction.) See, concrete can easily handle compressive (a.k.a. crushing) forces, but tensile forces (the kind that pulls things apart) make it weak in the knees. Steel, on the other hand, performs beautifully under tension, so the combo of the two is a match made in heaven. Rebar is so prevalent – and loved – that some people do crazy things with it like create sculpture and (very uncomfortable) furniture. To each his own.
See also: core drilling