If used as an adjective to describe a type of surgery in which a portion is removed, however, a semicolon is preferred.

But seriously, folks. When used in that context, the prefix used is "hemi-", and the full term is hemicolectomy, often done when a scary-looking polyp is found.

So, now - is there any reason (rhyme there is, aplenty) why sometimes the language chooses hemi-, or semi-, or demi-, when it wants to indicate half?