Postprandial means happening right after a meal. Doctors use it in a straight, serious way: postprandial blood sugar is the sugar in your blood after you eat, and they may ask you to wait two hours after food before a test. In ordinary English it often sounds playful or a little fancy — a postprandial nap is the sleepy stretch after lunch, said with a smile, not as a clinic note. You will meet it in health writing and in jokes much more than in street talk; most people just say “after lunch” or “after dinner.” Though actually, the first half is not the mail. Post- here only means after. Prandial by itself is a rare old word for “about a meal”; postprandial is the piece students actually see.

餐後的（日常多說「飯後」；體檢單上的「餐後血糖」就是這個）