A line that is broken at regular intervals. Sometimes it consists of a series of dots, but more commonly it is actually made up of dashes.

example of a dotted line:
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Dotted lines often indicate where paper (such as coupons) should be cut (by scissors). Other times, one might serve as a baseline above which a signature should be affixed. In yet other instances, a dotted line may denote a border line between political zones/regions on a map.