* Co-commentator: This is the most likely meaning. It refers to a person who works alongside another commentator during a broadcast, offering insights and analysis. For example, you might see "John Smith and Jane Doe will be the co-commentators for the game tonight."
* Company: This could be a shortened version of "commentary company," a company specializing in providing commentary services.
* Collaboration: "Comment co" could be a shorthand way of referring to a collaborative effort between two or more individuals or groups to create commentary.
To understand the precise meaning, you would need more context. Can you provide me with the sentence or situation where you encountered "comment co"?