It means that they are sharing credit. There is more than one author.
It means that more than one author wrote a book/article together.
Generally co-author should be hyphenated, but the relaxed rules of modern times often present coauthor as one word
Examples of co are cooperate, coworker, coauthor and so on.
According to the sources I've found on a quick search, you should hyphenate 'coauthor', i.e., it would better be: "co-author".
with.
No such substance as 'CaCo2'. Do you mean calcium carbonate, in which case the formula is 'CaCO3'? or do you mean an alloy(mixture) of 1 part calcium(Ca) to 2 parts cobalt(Co)?
conspirators or co-conspirators
No, typically "co-owner" is not capitalized unless it is part of a formal title or used as the first word in a sentence.
The prefix "co-" in words like co-worker or co-operative means "together" or "jointly." It signifies that the individuals mentioned are working or operating together in some way.
There was no one co-author. There was a group of five men who helped to write the Declaration of Independence. These men were Thomas Jefferson, Robert Livingston, Ben Franklin, John Adams, and Robert Sherman.
The Latin word adjutor or adiutor means "helper". The English word co-adjutor comes from it.
I believe it is technically one word, but is hyphenated, like this: CO-WORKER