junk mail

noun

1. unsolicited commercial mail or email.

junk mail

noun

1. untargeted mail advertising goods or services

Word History and Origins

Origin of junk mail¹

First recorded in 1950–55

Idioms and Phrases

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]