If you trust Merriam-Webster, apparently the plural can be either rebar or rebars. I've never heard "rebars" used, but then again I don't work in an industry that uses or specifies it...

http://www.merriam-webster.com/dictionary/rebar

I always thought that rebar was specified either by weight or length. Therefore I would suspect that the term 'rebar' would be used, as in "300 lbs of #4, grade 40, rebar" or "16 30 foot sections of #4, grade 40, rebar".

John R. Baker, P.E.
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To an Engineer, the glass is twice as big as it needs to be.

There are two industries I know of that use rebar: construction and computing.

In MS Windows, a rebar is basically a moveable toolbar or toolband. http://msdn.microsoft.com/en-us/library/windows/de... It was probably called a rebar because "it sat on top of a window". It can also sit on the side or under a window but they didn't think about that when they named it. In computing, programmers will use rebars and toolbars interchangeably and rightly or wrongly, they have added an s to the end of the word.

"Tie those two rebars into that ligature"

or

"Tie those two rebar into that ligature"

I know which one sounds better to me!

http://julianh72.blogspot.com

I work in the materials inspection industry in the US, and I hear the word "rebar" used only as a collective plural noun for reinforcing steel bars. When a specific individual piece of rebar is indicated, it is usually the singular noun "bar" or "piece of rebar". For example: "We are expecting the #9 rebar to be delivered tomorrow" [collective plural] OR "Tie those #9 bars to the mat" / "Get that piece of rebar off of the deck" [specific individual]. When someone says "rebars" it really stands out as sounding amateurish.

Since "rebar" is a contraction of "reinforcing bar", I'd guess that the rules for the original long form can still apply: "rebars" for plural.

STF

No sparweb, no. Custom and practice have their place, and your post makes you sound like some kind of Aeronautical engineer... (I kid, gently, I hope).

CEL,
Don't you know how hard it is to interact with all you so-called-engineers from inferior industries, stepping carefully around your hodge-podge rules of thumb and 19th century ways? Some days it's all I can do not to admonish you guys for not being more like us members of this more elevated discipline, aerospace, which is firmly rooted in the 20th century, like it should be!

Right now I need an animated smiley GIF that shows an aeronautical engineer building the rocket, and a civil engineer building the target.

STF

Hahahaha.... Love it.