An infinite interval of integration refers to when one or both limits of integration in an integral are positive or negative infinity. This means that you are integrating over an unbounded range.
Related terms
Finite Interval of Integration: Refers to when both limits of integration in an integral are finite numbers, meaning there is a definite range over which you are integrating.
Definite Integral: An integral where both limits of integration are finite numbers, resulting in a single numerical value as the outcome.
Improper Integral (as defined above): An improper integral can involve integrating over an infinite interval as well. Both terms are interconnected.