Sidenote vs. Side Note – Which is Correct?
Sidenote and side note are both correct American English terms for an additional comment or brief digression. Sidenote is the closed form, while side note is the open form. Use either in casual or formal writing, although side note may look more traditional and immediately clear to readers in context.
Sidenote or Side Note – Which is Correct?
Sidenote and side note are both valid spellings. They refer to a short additional comment, an aside, or a note that supplements the main discussion without being central to it.
Side note is the traditional two-word form and may be especially clear when the phrase is used conversationally: “As a side note, the meeting has been moved.” Sidenote is a closed compound noun that is common in edited writing, publishing, academic discussion, and digital communication.
The two forms usually have the same meaning. The choice is primarily a matter of style, consistency, and context rather than correctness. When referring specifically to a note placed in a book’s margin or beside the main text, side note may sound more immediately descriptive. When using the word as an established noun for an aside, sidenote is concise and natural.
The Best Trick to Remember the Difference
Think of side note as two separate ideas: a note placed on the side. Think of sidenote as the compact dictionary-style version of that same idea. If the phrase follows “as a,” both forms work: “as a sidenote” and “as a side note.” Choose one spelling and use it consistently throughout the same document.
| Word | Part of Speech | Meaning | Example |
|---|---|---|---|
| sidenote | Noun | An additional comment or brief digression | As a sidenote, the original plan was much more ambitious. |
| side note | Noun | An additional comment or note placed apart from the main point | As a side note, please save a copy of the document. |
How to Use Sidenote
Sidenote is a noun used for a secondary observation, clarification, or brief departure from the main subject. It often appears after the phrase “as a sidenote,” which signals that the following information is useful but not essential to the central argument. The word works in formal essays, reports, articles, and casual messages.
Because sidenote is a compact compound, it can look polished and economical in professional or academic prose. However, it should not be overused to introduce information that is actually important to the main argument. If a point matters significantly, present it directly instead of labeling it a sidenote.
Example 1: As a sidenote, the museum offers free admission on the first Sunday of every month.
Example 2: The author includes a useful sidenote about the historical origin of the phrase.
Example 3: A sidenote in the report explains why the final figures differ from the preliminary estimates.
Etymology of the Word Sidenote
Sidenote is a compound formed from side and note. The word developed from the idea of a note written beside or apart from the main text. Like many English compounds, it can appear first as two words and later become closed as usage becomes established. The open form side note remains fully acceptable.
How to Use Side Note
Side note is the open compound form of the noun. It describes a secondary remark, an aside, or a note positioned beside the principal text. It is particularly natural in conversational phrases such as “as a side note” and “on a side note,” although “as a side note” is generally the smoother and more idiomatic expression.
The open spelling can help readers process the meaning immediately because each component retains its ordinary meaning: something on the side and a written or spoken note. It is a strong choice when clarity is more important than compactness.
Example 1: As a side note, the author revised this chapter several times.
Example 2: The editor added a side note to explain the unfamiliar technical term.
Example 3: On a related side note, the company has opened a second office downtown.
Etymology of the Word Side Note
Side note combines the noun side, meaning an adjoining or secondary position, with note, meaning a brief written or spoken observation. The phrase developed naturally from the literal practice of writing comments beside a main text. The closed form sidenote represents the same compound after the words became more closely associated.
Related Concepts
Understanding related grammar and writing concepts makes it easier to use sidenote and side note appropriately.
- Aside: An aside is a comment that temporarily moves away from the main subject. It may be spoken in conversation, included in an essay, or used as a dramatic device in a play.
- Parenthetical expression: A parenthetical expression adds supplementary information to a sentence. It may be enclosed in commas, parentheses, or dashes, depending on how closely it relates to the main thought.
- Marginal note: A marginal note is written in the margin beside a page’s primary text. It is more specifically associated with physical books, manuscripts, and annotated documents.
- Digression: A digression is a departure from the main topic. Unlike a short sidenote, a digression can become lengthy and may significantly interrupt the original line of thought.
Examples from Media and Literature
The following examples show how both spellings can appear naturally in discussions of books, films, journalism, and everyday communication:
- Books: A literary critic might write, “As a sidenote, the novel’s setting is based on the author’s childhood home.”
- News articles: A journalist may add, “As a side note, the city’s public transportation system is also undergoing major renovations.”
- Film reviews: A reviewer could observe, “The director’s use of practical effects is impressive; as a sidenote, several scenes were filmed in a working theater.”
- Academic writing: A researcher might include a sidenote explaining that a term has a different meaning in another field.
- Everyday messages: Someone might write, “As a side note, remember to bring your identification to the appointment.”
Practice Exercises
Choose the correct word to complete each sentence. In every case, both sidenote and side note are grammatically possible; select the form that best matches the stated style preference.
- As a ______, the library will close early on Friday. (Use the open form.)
- The article contains a helpful ______ about the history of the building. (Use the closed form.)
- As a ______, please check that your contact information is correct. (Use the open form.)
- The editor included a brief ______ to clarify the statistic. (Use the closed form.)
- Which spelling is preferred in a document that consistently uses open compounds? (Choose the appropriate form.)
Answer Key
- side note
- sidenote
- side note
- sidenote
- side note
Sidenote Synonyms
| Synonym | Definition |
|---|---|
| aside | A secondary remark or brief departure from the main topic |
| digression | A temporary movement away from the central subject |
| additional comment | Information added after or beside the main statement |
| parenthetical remark | Supplementary information inserted into a sentence or discussion |
Side Note Synonyms
| Synonym | Definition |
|---|---|
| aside | A comment that is related to, but separate from, the main point |
| marginal note | A note written beside the main text, especially in a book or document |
| footnote | An explanatory or bibliographic note placed at the bottom of a page |
| observation | A comment or thought added to a discussion |
Frequently Asked Questions
Question 1: Is “sidenote” one word or two?
Both sidenote and side note are accepted spellings in American English. The closed form is one word, while the open form consists of two words.
Question 2: Which is more common, “sidenote” or “side note”?
Usage varies by publication, subject, and style preference. Side note is highly familiar and transparent, while sidenote is a well-established compact compound. Neither form is inherently incorrect.
Question 3: Should I write “as a sidenote” or “as a side note”?
Both phrases are correct. Use “as a side note” if you prefer the traditional open spelling, or “as a sidenote” if your style guide or surrounding text favors closed compounds.
Conclusion
Sidenote and side note are both correct terms for an additional comment, aside, or secondary observation. The closed form is concise, while the open form may offer slightly greater visual clarity. Choose one according to your preferred style and apply it consistently. Pro tip: Consistent spelling and careful word choice help make professional writing look polished and trustworthy.
