Here's why:
* Telegraph: This word was coined in the 19th century and combines the Greek words "tele" (meaning "far") and "graphein" (meaning "to write"). It refers to the system of long-distance communication using electrical signals.
* Telegram: This word is a derivative of "telegraph" and simply means a message sent via the telegraph.
So, the root word "telegraph" is the foundation of the word "telegram."