To debase means to lower the quality, value, or dignity of something. When you debase something, you make it less pure, less worthy, or less respected than it was before.

A gold coin debased with copper might look golden on the outside, but it's worth less than pure gold. People who discovered the deception felt cheated because the coin's value had been lowered in a sneaky way.

Today we use debase more broadly. A student who copies someone else's work debases their own education by making it less valuable. When people use vulgar language in a serious discussion, they debase the conversation by dragging it down from thoughtful exchange to mere insults. A movie sequel that adds crude jokes to a previously elegant story debases the original.

The word carries a sense of corruption or contamination. You don't debase something by accident: someone makes a choice to add something inferior or to lower standards.