How major style guides rule on "e-book"
Most style guides retain the hyphen for 'e-' prefixes (e-book, e-commerce); 'email' is the notable exception.
The disagreement on "e-book" is an example of hyphenation rules for common prefixes, 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) | e-book |
| Chicago Manual of Style | e-book |
| MLA Handbook | e-book |
| APA Publication Manual | e-book |
| Merriam-Webster Dictionary | e-book (also ebook) |
What the divergence actually means
Unlike many compound-modernization decisions where style guides eventually converge, "e-book" 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 "e-book", 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 "e-book (also ebook)", 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 "e-book" / "ebook" pair on its Language-Change Index, a five-stage scale measuring whether a once-disputed form has been accepted into Standard English. For hyphenation rules for common prefixes, 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 "e-book" reflect not disagreement about correctness but different audiences and editorial pressures.
Editorial context
In formal editorial contexts governed by major US style guides, the hyphenated e-book endures as the preferred form to clearly delineate the e- prefix from its root, a convention rooted in early 1990s tech journalism where compounds like e-mail set the pattern. Yet a persistent register split thrives in informal digital communication and tech-savvy online writing, where ebook gains traction for its streamlined appearance in URLs, app interfaces, and social media, spaces unbound by print-era rules. This divide mirrors broader prefix evolution, as seen with email's unhyphenated dominance by the mid-2000s, but e-book resists similarly due to its relative novelty. Corpus data from Google Books Ngrams illustrates the formal skew, with e-book vastly outpacing ebook in published volumes through 2019. Consider tech blogs erring toward brevity: Our latest ebook on Python programming is now available for free download.
Cross-references
For the dictionary entry, frequency data, and pronunciation of e-book, see the main word page. For other style-guide spelling decisions in this category, browse all style-guide spelling rulings.