Abbreviation at End of Sentence
Summary
If an abbreviation ending in a period also ends a sentence, don’t add another period. Use just one period, not two.
- Incorrect: The phone rang at 3 a.m..
Correct: The phone rang at 3 a.m. - Incorrect: They sell all kinds of used cars: hatchbacks, sedans, etc..
Correct: They sell all kinds of used cars: hatchbacks, sedans, etc.
If an abbreviation is enclosed in parentheses, use a period after the closing parenthesis to end the sentence.
- Incorrect: We treat all small animals (dogs, cats, hamsters, etc.)
Correct: We treat all small animals (dogs, cats, hamsters, etc.).
But if the sentence with the abbreviation is entirely enclosed in parentheses, don’t add another period to end the sentence.
- Incorrect: Night comes early in winter. (It gets dark by 4 p.m.).
Correct: Night comes early in winter. (It gets dark by 4 p.m.)
Also don’t add another period if the abbreviation appears within quotation marks at the end of a sentence.
- Incorrect: They replied, “We book tickets, stays, tours, etc.”.
Correct: They replied, “We book tickets, stays, tours, etc.”
Use an ellipsis as usual after an abbreviation. (Don’t omit the period.)
- Correct: Pesticides harm butterflies, bees, etc. . . . They also contaminate groundwater.
Use question marks and exclamation points as usual after an abbreviation that ends in a period. (Don’t omit the period.)
- Correct: Does Anita still work at Nusquam Inc.?
- Correct: He wakes up every day at 3 a.m.!
Period after abbreviation
If an abbreviation that ends in a period appears at the end of a sentence, don’t add another period. Never use two periods to end a sentence.
- Incorrect: They serve cakes, cookies, etc..
Correct: They serve cakes, cookies, etc. - Incorrect: Maya usually wakes up at 6 a.m..
Correct: Maya usually wakes up at 6 a.m. - Incorrect: We haven’t yet reviewed the paper by Dash et al..
Correct: We haven’t yet reviewed the paper by Dash et al. - Incorrect: Poco works at Nusquam Inc..
Correct: Poco works at Nusquam Inc.
Not all abbreviations end in periods. If an abbreviation does not itself end in a period, place a period after it as usual to end the sentence.
- Correct: Rita wants a car with a high rpm.
- Correct: Minerva Dash is our new CEO.
- Correct: The caterpillar measured 20 cm.
Abbreviations with two or more capital letters usually don’t contain periods: DNA, TV, ATM, PhD. Abbreviations with lowercase letters often contain periods (a.m., e.g., i.e., etc.), but periods are generally omitted in scientific and technical abbreviations (bhp, ppm, mph) and abbreviated units of measurement (km, ml).
Abbreviation in parentheses or brackets
If an abbreviation ending in a period appears within parentheses (or brackets) at the end of a sentence, use another period after the closing parenthesis to mark the end of a sentence.
- Incorrect: They serve all kinds of confectionary (cakes, cookies, etc.)
Correct: They serve all kinds of confectionary (cakes, cookies, etc.). - Incorrect: Applications will not be accepted after the deadline (6 p.m.)
Correct: Applications will not be accepted after the deadline (6 p.m.). - Incorrect: To cite an edited book, use the abbreviation ed. or eds. in parentheses: M. Dash (ed.)
Correct: To cite an edited book, use the abbreviation ed. or eds. in parentheses: M. Dash (ed.).
However, if the abbreviation is part of a sentence entirely contained within parentheses, don’t add another period after the closing parenthesis. (The sentence has already ended within the parentheses.)
- Incorrect: If you’re ever in Nusquam, you should visit the Pouthena Bakery on Nulle Street. (They serve the best cakes, cookies, etc.).
Correct: If you’re ever in Nusquam, you should visit the Pouthena Bakery on Nulle Street. (They serve the best cakes, cookies, etc.) - Incorrect: They refuse to accept submissions after the deadline. (For some reason, this deadline is always 3:33 a.m.).
Correct: They refuse to accept submissions after the deadline. (For some reason, this deadline is always 3:33 a.m.) - Incorrect: It has been conclusively established that life is meaningless. (For a detailed discussion, see Dash et al.).
Correct: It has been conclusively established that life is meaningless. (For a detailed discussion, see Dash et al.)
The punctuation marks called parentheses in American English are known simply as brackets in British usage.
Ellipsis after abbreviation
When an abbreviation appears at the end of a sentence that ends in an ellipsis, don’t omit the period for the abbreviation. Use both the period and the ellipsis: four periods, not three.
- Incorrect: Marine mammals are seals, whales, otters, etc. . .
Correct: Marine mammals are seals, whales, otters, etc. . . .
If an abbreviation followed by an ellipsis appears between sentences, the period marking the end of the previous sentence is retained. If that sentence ends in an abbreviation, use just the one period for both the abbreviation and the end of the sentence, and three for the ellipsis: four periods in all, not five.
- Original: Wake up at 6 a.m., when the day is still full of possibility. Having completed all your work by afternoon, have a calm and relaxing evening. You can then go to bed early. Or so they say. In reality, the day is over at noon.
Shortened: Wake up at 6 a.m. . . . You can then go to bed early. . . . In reality, the day is over at noon.
In academic writing, spaces are generally used between the dots of an ellipsis, while in news copy, an ellipsis is treated as a three-character word, and spaces are omitted. Both styles are correct: the Chicago Manual of Style, APA Publication Manual, and MLA Handbook recommend using spaces, while the AP Stylebook suggests omitting them.
- You can then go to bed early. . . . In reality, the day is over at noon.
orYou can then go to bed early. … In reality, the day is over at noon.
Abbreviation in quotation marks
If an abbreviation ending in a period appears within quotation marks at the end of a sentence, don’t add another period. The period after the abbreviation suffices to mark the end of the sentence.
- Anita replied, “We close at 9 a.m.”
- Poco said, “I’ll send you a list of requirements, costs, etc.”
Even if the abbreviation appears in quotes within quotes (i.e., within single and then double quotation marks), one period suffices. Don’t add another period to end the sentence.
- Lulu said, “Rita clearly told me ‘9 a.m.'”
Question mark and exclamation point after abbreviation
Use a question mark or exclamation point as usual at the end of a question or exclamation that ends in an abbreviation, even if the abbreviation itself ends in a period. Don’t omit the period.
- Correct: Did you say she called at 4 a.m.?
- Correct: Where can I buy balloons, flags, masks, etc.?
- Correct: Does Poco still work at Nusquam Inc.?
- Correct: Is midnight 12 a.m. or 12 p.m.?
- Correct: I can’t believe it’s 4 a.m.!
Other punctuation with abbreviations
Use commas, dashes, semicolons, and other punctuation marks as usual after an abbreviation that ends in a period.
- At 4 a.m., the bell rang.
- We sell party supplies—balloons, flags, masks, etc.—at discounted rates.
- She said it was 4 a.m.; I believed her.
- Business hours are 9 a.m.–6 p.m.