- Junk mail is defined as unwanted catalogs, advertisements, coupons and other offerings that are delivered to you via postal mail or email.
An email encouraging you to enter a sweepstakes is an example of junk mail.
A box filled with junk mail.
advertisements, solicitations, etc. mailed in large quantities, usually by third-class mail
Third-class mail, such as advertisements, mailed indiscriminately in large quantities.
junk mail - Computer Definition