What is at the end of a rainbow?

“A pot of gold”

This is a common myth associated with rainbows, but the riddle specifically asks for what is literally at the end of the word 'rainbow', not a fictional treasure.

“The colors of the rainbow”

While colors are often found in a rainbow, the riddle is looking for a specific letter found at the end of the word itself, not the visual aspect of the rainbow.

“A cloud”

Clouds are often seen near rainbows, but again, the riddle focuses on the word 'rainbow' rather than its physical characteristics.