1. In another way; differently: She thought otherwise.
2. Under other circumstances: Otherwise I might have helped.
3. In other respects: an otherwise logical mind.
4. Used to indicate a category to which the preceding adverb does not apply: All the students, dressed suitably and otherwise, went on the field trip.
5. Or else.
If not; or else.
Other than supposed; different: The evidence is otherwise.
[Middle English, from Old English (on) ōthere wīsan, (in) another manner : ōthre, dative of ōther, other + wīsan, dative of wīse, manner; see WISE2.]
Usage Note: When used to connect two related clauses, otherwise is usually classified as a conjunctive adverb, which by grammatical tradition should be preceded either by a semicolon or by a period. But because otherwise often means "or else" in these contexts, and or else behaves as a subordinating conjunction, otherwise is often treated as a conjunction and is preceded by a comma, sometimes even in publications that predominantly treat it as a conjunctive adverb. This usage tends to be more common in narrative and dialogue: "Mr. Radish is flabby, slope-shouldered, otherwise he'd be tall as Ira Early. But lacking what you'd call dignity, stature" (Joyce Carol Oates). Copyeditors tend to prefer the more traditional punctuation using the preceding semicolon or period. The Usage Panel supports this practice without roundly condemning the alternative. In our 2006 survey, some 51 percent rejected a sentence in which otherwise is preceded by a comma (The store must be open, otherwise there wouldn't be anyone inside). But 70 percent said that this sentence would be acceptable if a semicolon was used. · When introducing a new clause, otherwise is often followed by a comma: "On Thanksgiving, the staff got an hour for dinner; otherwise, the schedule was the same" (Janet Reitman). A preceding comma is required when otherwise is used to introduce a contrasting phrase and means "in another manner:" The student has symptoms of pertussis, otherwise known as whooping cough.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.