What is the meaning of the prefix col?

The prefix "col" or "colo" refers to the fact that a word which possesses the term has has something to do with the intestinal system. The Greek word "kolon", upon broad translation, means "large intestines". So the English word colon is a direct use of the Greek word for large intestines. Here is an example of the use of "col": Escherichia coli (more commonly known as E. coli) was first isolated by Theodor Escherich. The Escherichia part of the scientific name of the bacterium reflects the contribution by Escherich and the coli part indicates that the bacterium came from the intestinal tract. One thing to remember is that E. coli is a normal part of the human intestinal system and it is only certain strains of E. coli (like O157:H7) that are giving E. coli a bad name. Notice that "coli" is, in fact, a word derived from "col". Link for reference: http://myword.info/sendword.php?colo_1-a