Dictionary.net

• a line made up of dots or dashes; often used to indicate where you are supposed to sign a contract; "just sign on the dotted line"

2006 - WordNet 3.0
By Princeton University

• a line made up of dots or dashes; often used to indicate where you are supposed to sign a contract; "just sign on the dotted line"

2011 - English Dictionary Database
By DataStellar Co., Ltd