A Latin phrase that translates into English as “my mistake” or “my fault”. To emphasize the message, the adjective “maxima” may be inserted, resulting in mea maxima culpa, which would translate as “my most [grievous] fault.”
MoMilli adds: In the Catholic penitentiary rite, the new translation reads “through my fault, through my fault, through my most grievous fault.” Tom translated Latin in high school for sport.