Anyone run into terms on here that they have no clue what they mean?

Lol okay so I'm a first time mom here and I am not familiar with the pregnancy lexus. I keep seeing "di/di twins" and I have no idea what it means. If anyone knows, what does this mean? Lol. Also, when I saw FTM, I was confused because I thought it meant female to male transgender! Anyone else not know what some of these terms are? Haha 😂😅