# Do I draw a line or rule on a paper?

When I use a ruler and a pen, is it a line or a rule that I draw? What are the dimensions of the line/rule, length and width, or length and thickness?

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I have never thought about the fact that it could be different in wordprocessing and "classroom" use. My application is indeed a word processor, so I will take 'rule' into account, but now I know that I am not wrong if I say "With this you draw a line from ...". – topskip Nov 28 '11 at 12:35

It's probably a line, especially for a math problem. Dimensions are in inches or centimeters, according to the problem. Thicknesses are in fractions of an inch or in mm.

I have seen rule for word processing or typesetting. Dimensions are again in inches or centimeters, but thicknesses here are in fractions of points.

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Classically, (ie mathematically), you would rule a line, which has, of course, neither width nor thickness. (the apparent thickness being experimental error).

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The line that is drawn in a real world on a real paper is a representation of a geometrical line (which has no thickness). So, there is no problem there. – Unreason Nov 28 '11 at 13:18

I agree with others that what you draw with a ruler is a line. The OED gives a straight line drawn on paper; specifically, one of the lines of a stave of music as one of the definitions of rule, but states that such use is now rare. I, too, recall that in geometrical terms, a line has length but no width.

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Thanks for pointing me to the OED. Sometimes I forget about its existence. – topskip Nov 28 '11 at 12:40
@Patrick: I find it indispensable, but it requires a paid subscription. – Barrie England Nov 28 '11 at 12:42
In geometry, a line segment has length. A line extends infinitely in both directions. – hammar Nov 28 '11 at 19:14

In contemporary English, it's a line that you draw, and you'd measure its length and its thickness. Width would be for a two-dimensional figure, like a rectangle.

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Any line you draw on paper has three dimensions, length, width, and depth (or thickness). One says, "I drew a line using a ruler," "I ruled a line using a straightedge," "I ruled a line with a pen and rule," etc.

In vulgar parlance some speak of line thickness when they mean width. In logical terms, and in CAD programs, the measurable dimensions of a drawn line are length and width. Width varies as the pen- or pencil-tip width varies. Thickness is the depth of the line on the drawing surface, typically sub-micrometer, and varies with ink or pencil lead properties, drawing pressure, paper surface qualities, etc.

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