General meaning:
* Discount
* Reduction
* Lowering
* Price cut
* Sale
* Mark-down (this is often used interchangeably with markdown)
Technical meaning:
* Markup language (specifically referring to the lightweight markup language used for writing web content)
* Plain text formatting (describing its simplicity)
* Lightweight markup (emphasizing its minimal syntax)
Informal meaning:
* Cheapen
* Devalue
Remember to choose the word that best fits the specific context in which you are using it.