Jun 182013

A lot of good writers use the semicolon well; a lot of bad writers abuse it. There’s one very common semicolon error; this one.” — Ben Yagoda

The semicolon (;) is one of my all-time favorite punctuation marks. It is most often used to draw attention to the connection between two related ideas. Another way to think about the semicolon is as a stand-in for the comma and conjunction combination (replacing “, and” or “, but”). The phrases on each side of the semicolon must be independent clauses (i.e., complete thoughts), and no conjunction is required. For example:

  • The trial results were entered into the database; all records were coded to preserve anonymity.
  • Ten patients were admitted with disease symptoms; two died within 48 hours.
  • Pro-tip — If all else fails, using a semicolon is a great way to get around starting a sentence with a number: The cohort consisted of 82 patients with Alzheimer’s disease; 15 patients were under 55 years of age.

Semicolons are likewise used when joining two independent clauses with a conjunctive adverb, such as however, indeed, or therefore (i.e., any word/phrase that would be considered an introductory clause in a standalone sentence):

  • The two species are closely related; however, Ursus maritimus is better adapted to cold weather.
  • Contrary to our expectations, sales did not fall in the second quarter; indeed, we sold more widgets in April than in any other month.

The semicolon can also be used instead of commas to separate items in a list when one or all of the items already contain commas. This usage is especially common in academic writing and can even be used in the Methods or Results sections. Note that when semicolons are used to separate items in a list, the final semicolon before and is required.

  • The countries were divided into three groups based on their geography: China, South Korea, and Japan; the UK, the US, and Canada; and Germany, France, and Italy.
  • Patients were excluded if they had a family history of drug or alcohol abuse; had kidney, heart, or liver disease; were pregnant or nursing; or were undergoing treatment for another psychiatric disorder.
  • The participants averaged 36 hours of training (range, 22-57; median 32).
  • The B-actin antibody (1:1000 dilution; Abcam, Cambridge, MA) was used as a control.

Using semicolons is an excellent way to introduce variety into the sentence structure in your writing. For a paragraph with many short, choppy sentences, linking two of those sentences with a semicolon can improve the overall flow of the text. Similarly, a long sentence with many clauses can often be divided with a semicolon to make it easier to read while still emphasizing the connection between ideas. However, as with other less-straightforward sentence structures, these constructions should be used sparingly; readers will notice if every other sentence contains a semicolon. We hope that today’s tips and examples help encourage you to use the semicolon in your own writing! If you have questions about using semicolons, leave a comment or send us an e-mail. AJE wishes you the best!

Today’s editing tip was brought to you by Jacqueline Chretien, PhD.

AJE has helped tens of thousands of international researchers produce publication-ready manuscripts with our academic and medical editing services. To find out more about how our subject-area experts can polish your writing, visit http://www.aje.com/en/editing.

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Editing Tips Team

The AJE Editing Tips Team brings you helpful tips authored by AJE's experienced Managing Editors and In-house Editors to improve your academic English writing. Click here to find out more about the authors behind the Editing Tip of the Week.

  9 Responses to “Editing Tip of the Week: Semicolon Usage”

  1. Thanks for the tips – very useful :-) One example used in the article particularly interested me, and it was this one: “Patients were excluded if they had a family history of drug or alcohol abuse; had kidney, heart, or liver disease; were pregnant or nursing; or were undergoing treatment for another psychiatric disorder.” The second, third and fourth items are not technically clauses (no subject for the verbs), and I’d previously understood that the semicolon could only be used to separate segments on a list which are not full clauses if that list was introduced with a colon. Always good to learn something new!

    • SquareSparrow,

      I’m glad you found the tips helpful! I’m unaware of any proscription against semicolons in that context without a colon to introduce the list. The Chicago Manual of Style, for example, offers this example of semicolons in a list: “You are advised to pack (1) warm, sturdy outer clothing and enough underwear to last ten days; (2) two pairs of boots, two pairs of sneakers, and plenty of socks; and (3) binoculars and a camera” (CMS 15th ed., 6.126). The colon becomes more important when the introductory information is an independent clause, which is not the case in the example you cite.

      Thanks again for your comment!

      Best wishes,
      Ben Mudrak
      Education Program Manager

  2. Thank you very much for this tip. The examples given are excellent.

  3. Wonderful post on the semicolon. And yes, the mark does, as you said, draw attention to “the connection between two related ideas”.

    However, with one or two exceptions, grammarians have not made the nature of the connection clear. And when you inspect the examples that illustrate use of the semicolon, you see that the examples imply that the predominant or exclusive connection is coordinative: The semicolon stands in for “and”.

    I studied these connections and discovered that they are surprisingly diverse, even intriguing. Coordination is only one connection that the semicolon sustains. My article (“The Enigmatic Semicolon”) is posted on my website http://www.medlinguistics.com, and can be viewed and printed out for free. Just click “Enigmatic Semicolon” on the left sidebar. Enjoy! Janet

    • Janet,

      Thanks for the kind words! You’re right, the connection between two ideas does often imply coordination, but that’s not always the case. I particularly like your example of a semicolon serving to provide contrast: “Survival vehicles don’t replicate themselves; they work to propagate their replicators.” Still, at the most basic level, the semicolon says “This is true; this is also true”; the writer is free to use items that should be coordinated, contrasted, etc.

      Best regards,

  4. I loved your article because, like you, I am a great believer, and advocate of, the semi-colon. I recently wrote an article for an editing colleague who exclaimed how much bothered she was by my enthusiasm for it. Despite my explanation and rationale for its use, she prefers that sentences are broken up by use of full stops! I disagree, but admit she is far more experienced in editing than me; I slunk away from our conversation feeling a little…deflated. Today I read your article and feel positively reassured, gratified and self-righteous; the semi-colon DOES have a place in writing and should be encouraged and used with flourish! Hurrah for the semi-colon I say!

  5. A version of this article first appeared on Expert Edge.

  6. [...] A version of this article first appeared on ExpertEdge. [...]