What does the Latin phrase "mea culpa", used in the Roman Rite, mean?

Through my fault, through my fault, through my most grievous fault…

CyanJaguar62, they chanted or sung it. Mesmerizing

They still said the Catholic mass in Latin when I was a kid and that phrase stuck with me. Kinda like "ecum spiri tu tu o" (don't know how it was actually spelled) because it sounded like a phone number

No, it literally means my (mea) fault (culpa). If you want to add the word "through" you need some form of via (through).

Thanks for the correction. I always thought the phrase was nominative.