When we say a function is "defined" at a certain point, it means that the function has an output value for that specific input. However, even if the limit exists, it does not guarantee that the function will have a defined value at that particular point.
Related terms
Discontinuity: A point where a function fails to be continuous due to either jump discontinuity, removable discontinuity, or infinite discontinuity.
Removable Discontinuity: A type of discontinuity where removing or redefining a single point makes the function continuous again.
Vertical Asymptote: A vertical line beyond which the graph of a rational function approaches indefinitely, but never crosses.