Q. I am editing a medical index using the “word-by-word” system, and having some trouble with hyphenated words. Some terms, like “non-ionic,” feature a hyphenated word that is not a compound word. Does “non-ionic” come before “nonclostridial?” Also, do hyphenated compound words like “arterial-gas” come before or after a non-hyphenated compound word like “arterial oxygen?” Thanks—this is giving me a headache!

A. Ignore the hyphen after a prefix when indexing. “Non-ionic” should be alphabetized as though it were “nonionic,” in the way that the hyphenated compound “new-fangled” comes between “newel” and “Newfoundland” in CMOS 16.61 in the “Word by Word” column. (Note, however, that Chicago style does not normally hyphenate prefixes, following Webster’s, and would thus avoid that problem.) Hyphenated compounds come after all the open ones. (Again, see 16.61, where “new-fangled” comes after “new town,” etc.)