Electronic mail and Junk mail

Electronic mail noun - (computer science) a system of world-wide electronic communication in which a computer user can compose a message at one terminal that can be regenerated at the recipient's terminal when the recipient logs in.

Junk mail and electronic mail are semantically related. In some cases you can use "Junk mail" instead a noun phrase "Electronic mail".

Junk mail noun - Third-class mail consisting of advertising and often addressed to `resident' or `occupant'.

Electronic mail and junk mail are semantically related. Sometimes you can use "Electronic mail" instead a noun phrase "Junk mail".