Q. I have always changed cf. to see since CMOS states that it means “to confer; compare.” Of course, I query whether the author really does mean “compare,” but the majority of the time they mean to say “see.” Someone tells me that their dictionary says it is often used to mean “see also.” This doesn’t seem right to me—it’s an abbreviation for a Latin term; how can a dictionary change an actual meaning?
A. Dictionaries are not in the business of changing meanings: rather, lexicographers collect evidence on how people use words, and when a word is used pervasively and persistently to mean something, they list that meaning in the dictionary. After all, if you don’t know the meaning of a word, what good is it if the dictionary lists only the original, perhaps outdated meanings? You need to know what it means now.
That a meaning is listed in a dictionary doesn’t mean that the editors of the dictionary have put some stamp of approval or acceptance on it. Rather, they are stating a fact: this is one meaning of this word, a meaning documented by research and observation. Readers must decide whether that use is appropriate.
For a long time now, scholars have been using cf. to mean see also, and if the dictionary says that this is what readers now understand by it, I suppose many editors must be letting it stand.