co- = subordinate vs. co = equals
Many years ago using the prefix co- and co meant two different things. Now they are used interchangeably, but is this correct? I was taught if you used co- you were a subordinate and if you used co you were equals. An example. A co-pilot is subordinate to a pilot, however coauthors means both writers were equal in the endeavor. Once upon a time, a co-chairwas subordinate to the chair. Now co-chair and cochair are used flagrantly to mean the same thing, they are equally sharing the duties of chairperson. What are your thoughts on this?