Degenerate dimension

Sometimes when we talk about things that have different parts, we use big words like "dimension" to describe how many parts there are. But sometimes, we might have a situation where some of the parts are the same as others.

When that happens, we say that those parts are "degenerate." That's just a fancy way of saying they're not really different from each other.

So when we talk about a "degenerate dimension," what we mean is that there are some parts of something that are just the same as other parts. It's like if you had a puzzle with two puzzle pieces that looked exactly the same -- they wouldn't really be different pieces at all!

In some cases, this doesn't really matter for what we're trying to do or understand. But sometimes it can make things harder or more complicated. So when people talk about degenerate dimensions, they're usually trying to figure out how to deal with that extra complexity.