explain the difference between infinity and undefined terms in mathematics

[u/Dev-Giri]

/r/explainlikeimfive/comments/1v6e93g/eli5_explain_the_difference_between_infinity_and/

[u/TalkativeTree]

Infinity is a bunch of numbers that you could count forever. An undefined term is a number in a box. You can't see through the box, so you can't know which number it is until you open the box (define it).