- unsolicited commercial mail or email.
Origin of junk mail
First recorded in 1950–55
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
- untargeted mail advertising goods or services
Third-class mail, such as unsolicited advertisements and flyers, that is sent indiscriminately. For example, While we were on vacation the front hall filled up with junk mail. [c. 1950]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.