Most editors are failed writers (but then, so are most writers). One of the reasons they fail is by incorrect use of abbreviated Latin words. Here is an archive of such words, their meaning and use.
A.D. (anno Domini): "in the year of our Lord."
A.M. (ante meridiem): "before noon." Meridies means "noon" or "midday." The English abbreviation for ante meridiem means the time before noon and after midnight.
B.A. (Baccalaureus Artium): "Bachelor of Arts." A four year undergraduate degree.
circa: "about." Abbreviated c or ca, indicated uncertainty about a date.
confer: "compare." Abbreviated cf. Often used as "see" or "see also," what it really means is to invite readers to compare an author's discussion with that presented in another work.
e.g. (exempli gratia): "for example."
erratum: An error in printing or writing. An errata is a listing of such errors.
et al: Abbreviation for et alii (masculine), et aliae (feminime), and et alia (neuter) indicating "and other men" or "and other people;" "and other women;" and "and other things." Persons do not pronounce et al. "And others" is always said for et al.
etc. (et cetera): literally "and the rest" but in the modern it would be "and so on." Used only when speaking of things, not people.
e.g. (exempli gratia): literally "for the sake of example" but in the modern it would be "for instance." It is used correctly to introduce an example. It is used incorrectly to mean "that is" (see id est).
ibid.: Abbreviation of ibidem meaning "in the same place." Used to make reference to an identical source cited in an immediately preceding footnote.
i.e. (id est): "that is." Used to clarify a statement just made. Most frequently confused with e.g. (exempli gratia) "for example."
M.A. (Magister Artium): "Master of Arts." A higher university degree.
M.D. (Medicinae Doctor): "Doctor of Medicine."
N.B. (nota bene): literally "note well" but in the modern it would be "take notice." This calls attention to something important in a written document.
op. cit. (opere citato): "in the work cited." Used in a footnote to reference a work previously cited.
per se: "by or in itself," but perhaps better stated in the modern as "intrinsically."
P.M. (post meridiem): "after noon." See A.M. (ante meridiem).
P.S. (post scriptum): "written afterward."
Q.E.D. (quod erat demonstrandum): "which was to be demonstrated." Appended to solutions with the meaning that the proposition that was set out to be proved has been.
quid pro quo: "something for something." In the modern, "this for that," it means something given in return for something.
re: "concerning" or "regarding."
sic: "thus." Used to indicate an apparent misspelling or a doubtful word or phrase in a source being quoted.
via: "by way of' or "through."
vice versa: Literally "the change being turned," might be better stated in the modern as "conversely."
viz. (videlicet): Literally, "it is permitted to see," or better stated in the modern as "to wit." It is expressed orally as "namely" (not as viz).