The phrase "cabbage head" is used to refer to someone who is not very intelligent or who makes silly mistakes. It implies that the person's brain is like a cabbage, which is not very smart. Full definition
The pot should be able to hold the entire cabbage head easily. (whereismyspoon.co)
I've snuck a whole cabbage head into this sneaky casserole and no one ever knew. (all-thats-jas.com)
3 and 1/2 to 4 pound corned beef brisket Water (enough to just barely cover the meat) 3/4 cup white vinegar 1 small onion chopped 3 to 4 garlic cloves chopped 2 bay leaves Spice seasoning packet (packaged with the brisket) 1/2 large cabbage head cut into wedges 6 small potatoes peeled 6 carrots peeled and cut into large pieces (learnfromyesterday.com)