Ordinal definable
Ordinal definable means something can be described or defined in terms of a certain kind of order. Let's imagine you have a bunch of toys you want to put in order from your favorite to your least favorite. You might say "I like my teddy bear the most, then my doll, then my toy car, and finally my action figure." This is an ordinal definition because you are putting your toys in a specific order.
In math, things can also be ordinal definable. For example, the number 1 is ordinal definable because it is the first number in the counting order. The concept of "infinity" is also ordinal definable because it describes the idea of having an endless number of things.
So, when something is ordinal definable, it means it can be described or defined in terms of a specific order, like counting or ranking from highest to lowest.
In math, things can also be ordinal definable. For example, the number 1 is ordinal definable because it is the first number in the counting order. The concept of "infinity" is also ordinal definable because it describes the idea of having an endless number of things.
So, when something is ordinal definable, it means it can be described or defined in terms of a specific order, like counting or ranking from highest to lowest.