phinds said:
What's the difference between indeterminate and undefined?
"Indeterminate" is used in the context of limits, as
@jbriggs444 already said, and means that some work is required to determine whether they represent numbers. Some indeterminate forms are ##[\frac 0 0]##, ##[\frac \infty \infty]##, ##[\infty - \infty]##, and ##[1^\infty]##. Most textbooks write these forms in brackets to emphasize that they are "forms" rather than actual numbers.
The following limits are examples of the first three types I listed:
##\lim_{x \to 1}\frac{x^2 - 1}{x - 1}##
##\lim_{t \to \infty}\frac{t^2 + 2}{t^3 - 1}##
##\lim_{y \to \infty}y^2 - y^3##
These are called indeterminate forms because it's not obvious at first glance that they represent a number. By taking a limit and subsequent algebraic or other operations, one can determine that a limit actually exists or not.
As for undefined -- the division of any number by zero is undefined, as is taking the square root (or fourth root or any even root) of a negative number is undefined (if we're dealing with the real-valued square root function). In general, attempting to evaluate a function at a number not in its domain is undefined.