The problem is that the focus on the term “collusion” has had the effect of implying precision where there is essentially none. Meeting the standard of “proof of collusion” isn’t a matter of meeting a technical definition or threshold — it is a matter of persuading enough people that what we’re seeing is collusion. It is, in other words, a political judgment and, as with all things political, is extraordinarily subjective and vulnerable to all sorts of manipulations. The fuzziness of the current discourse may not matter much to the F.B.I., whose investigation will surely adhere to the letter of the law — but it might matter a great deal for how its findings play in the court of public opinion.

The use of the word has, for instance, allowed members of Congress handling the Russia investigation to tell us that they have not seen a scintilla of evidence of “collusion.” We now know that these congressional members had long been told by American intelligence officials that advisers to Mr. Trump might be working with the Russians to interfere in the election. That’s what use of the word “collusion” helped keep hidden.