The Collaborative International Dictionary of English v.0.48:

Col- \Col-\
   A prefix signifying with, together. See Com-.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Col \Col\, n. [F., neck, fr. L. collum neck.]
   A short ridge connecting two higher elevations or mountains;
   the pass over such a ridge.
   [1913 Webster]