"Ject" comes from the Latin word "jacere", meaning "to throw" or "to cast".
Here's how it breaks down:
* De-: A prefix meaning "down" or "away"
* Ject: The root word meaning "to throw"
* -ed: Past tense suffix
Therefore, "dejected" literally means "thrown down" or "cast down", which aptly describes the feeling of being disheartened or discouraged.