How major style guides rule on "vice versa"
Now fully naturalized in English; major guides drop both italics and hyphenation.
The disagreement on "vice versa" is an example of naturalized loanwords and italics conventions, the category of style-guide differences that most often confuses copy editors and creates inconsistency across long documents. Below is a guide-by-guide breakdown, drawn directly from the published editions cited.
| Style guide | Preferred form |
|---|---|
| AP Stylebook (2024–2025 Edition) | vice versa (no italics) |
| Chicago Manual of Style | vice versa (no italics) |
| MLA Handbook | vice versa (no italics) |
| APA Publication Manual | vice versa (no italics) |
| Merriam-Webster Dictionary | vice versa |
What the divergence actually means
Unlike many compound-modernization decisions where style guides eventually converge, "vice versa" continues to show genuine divergence between major guides. The AP Stylebook treats this as a settled call; Chicago Manual leaves more flexibility; and Merriam-Webster, as a descriptive dictionary, records both forms. Source: Chicago Manual of Style, 17th Edition
The APA Publication Manual aligns with AP and Chicago on "vice versa", though APA generally addresses spelling questions only when they intersect with statistical reporting or technical psychology vocabulary. Where the manual is silent, APA defers to Merriam-Webster as its standard reference. Source: APA Publication Manual, 7th Edition
Merriam-Webster lists "vice versa", which serves as the lexicographic baseline for U.S. style decisions. Because Merriam-Webster's entries reflect aggregated published usage rather than editorial preference, when a guide says "follow Merriam-Webster", as APA does, that effectively delegates the call to whichever spelling has dominated the published corpus. Source: Merriam-Webster Dictionary
Garner's Modern English Usage classifies the "vice versa" / "vice-versa" pair on its Language-Change Index, a five-stage scale measuring whether a once-disputed form has been accepted into Standard English. For naturalized loanwords and italics conventions, Garner's typically rates the dominant form at Stage 4 ("ubiquitous but objected to by traditionalists") or Stage 5 ("fully accepted"). Source: Garner's Modern English Usage, 5th Edition
Practical guidance for editors
For working writers, the practical rule is straightforward: in journalism, follow AP; in academic writing in the humanities, follow MLA or Chicago; in social-science publishing, follow APA; in book publishing, follow Chicago. When no house style applies, Merriam-Webster's main entry is the safest default. The differences across these guides on "vice versa" reflect not disagreement about correctness but different audiences and editorial pressures.
Editorial context
Published-corpus evidence underscores the triumph of the unhyphenated "vice versa," with Google Books Ngrams showing it vastly outnumbering "vice-versa" throughout the modern era, often by ratios exceeding 10:1 since the 1850s and climbing to 25:1 by the 1960s. This dominance reflects the phrase's evolution from italicized Latin import to seamless English idiom, unburdened by hyphenation that might imply novel compounding. The data reveal a sharp decline in hyphenated usage post-1920, aligning with broader trends toward de-hyphenating fixed phrases like "et cetera." Even so, "vice-versa" lingers at low frequencies in The rule applies to employees, vice-versa to contractors, especially in midcentury technical manuals and casual prose resistant to formal regularization. Such evidence contextualizes style-guide consensus as rooted in empirical print history rather than arbitrary fiat.
Cross-references
For the dictionary entry, frequency data, and pronunciation of vice, see the main word page. For other style-guide spelling decisions in this category, browse all style-guide spelling rulings.