Is conception the days of sex, or when sperm and egg meet or when the egg actually implants itself..how long after sex is true "conception"?

Not a medical word: Conception is not really a medical word. We could think about it as a multi-step process. Fertizilation is when the sperm and egg meet, a few hours after sex, and the sperm is able to penetrate the outer layer of the egg. Implantation of the fertilized egg, now called a zygote, and soon to be a blastula, happens several days later when it arrives in the uterus.