Q. 1. What is a "permanent impediment?"
A. 1. A "permanent impediment" consists of a situation that will never change during a marriage. For example, the couple has to be physically able to consummate the marriage by engaging in sexual intercourse with each other. A permanent biological inability to do this constitutes an impediment to marriage.
In simple words, the inability to have sexual intercourse with your potential future spouse is a permanent impediment that prevents a Sacramental Marriage from taking place.