If the expression obtained after any substitution during limit analysis does not give enough information to determine the original limit, it is known as an indeterminate form.

A mathematical expression can said to be indeterminate if it is not definitively or precisely determined. Certain forms of limits are said to be indeterminate when merely knowing the limiting behavior of individual parts of the expression is not sufficient to actually determine the overall limit.

Basically there are seven form of indeterminate 0 × ∞, 0/0, ∞0, ∞ − ∞, 1∞, 00 and ∞/∞.