Q. I know that Chicago recommends the dictionaries published by Merriam-Webster, but as a writer based in Canada is it possible to opt for a dictionary of Canadian English and still be in conformity with Chicago?
A. Chicago style allows for regional variations in spelling. Unless you are writing for a publisher that expects otherwise, it’s best to choose a dictionary that matches the variety of English you are writing. For matters of spelling, that source could be any high-quality standard dictionary. At the end of CMOS 7.1, where we recommend Merriam-Webster, we also refer readers to our bibliography for additional English-language dictionaries, including the Canadian Oxford Dictionary:
Barber, Katherine, ed. Canadian Oxford Dictionary. 2nd ed. Oxford: Oxford University Press, 2004. https://doi.org/10.1093/acref/9780195418163.001.0001.
The Canadian Oxford includes entries for “colour,” “defence,” and “kilometre”—each of which lists, as “also” variants, the standard US spellings: “color,” “defense,” and “kilometer.” It also includes Canadian terms like “bushlot” and “First Nation,” neither of which is in Merriam-Webster.