a line on a contract or similar document for a party's signature.
a line at which a sheet of paper is perforated or a piece of it is to be detached.
signature on the dotted line, full agreement to terms and conditions.
sign on the dotted line, to agree fully to terms or conditions.
Origin of dotted line
First recorded in 1770–75
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
a line of dots or dashes on a form or document
sign on the dotted line to agree formally, esp by signing one's name on a document
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012