Welcome to HealingWell!
D stands for diarrhea and C stands for constipation. You will see a lot of acronyms here. We also write BM for bowel movements. I can't think of any others besides the usual LOL (laughing out loud) and BTW (by the way).
Feel free to post any questions, comments, or concerns you have. We are a friendly crew and will be as supportive and helpful as we can.