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Rules on Abbreviations

The style for abbreviations has gone through a series of changes in the past few decades. The trend today is to drop the periods from most abbreviations used in writing. Within a document, however, periods may be used or omitted if the writer is consistent.



The style for abbreviations has gone through a series of changes in the past few decades. The trend today is to drop the periods from most abbreviations used in writing. Within a document, however, periods may be used or omitted if the writer is consistent. For example, if AM appears without periods in one sentence, do not use A.M. in another.

General Guidelines

Here are some general guidelines for using abbreviations.

  1. Forformalandbusinesswriting, internal periods are omitted for most abbreviations related to time, academic degrees, metric measures, organizations, institutions, and government agencies.

  2. Exceptforpersonalnamesandtitles, abbreviations with internal periods (e.g., N.W.) should not have a space after the first period.

  3. Forabbreviationsofpersonalnamesandtitles, insert space after the first period. (H. G. Wells, Lt. Col. Brice)

  4. Whenindoubtabouthowtostyleabbreviationsofpersonalor company names, always check with the individual or firm to see how they prefer the abbreviation to be written.

Personal Names and Titles

This section presents some general rules for the abbreviation of personal names and titles.

Personal Names. Avoid using abbreviations for given names except when transcribing a signature.

    • Dorothy Brandt not Dor. Brandt
    • Charles Villiard not Chas. Villiard

If the signature is written with abbreviations, follow the style of the author.

    • Yours truly, Geo. C. Kelly
    • Sincerely yours, L. K. Geng

Some publications and business writers omit the periods following initials. However, for convenience and clarity it is usually good practice to use periods with all initials given with names.

    • Caroline S. Wilson
    • Robert J. Edwards
    • T. J. Warshell
    • A. Teresa Valdez

If the person is referred to by initials only, no periods are used.

    • FDR (Franklin Delano Roosevelt)
    • LBJ (Lyndon Baines Johnson)
    • HD (Hilda Doolittle)

Titles Before Names. Social titles are always abbreviated whether used with the surname only or the full name. Notice which titles are used with or without periods. If you are in doubt about when to use periods with a social title, consult an up-to-date dictionary.

    • Mrs. Gloria Greenberg
    • Ms. Barbara Walnum
    • Mme Cecilia Payne
    • Messrs. Paul Mori and Norman Zuefle
    • Mr. Valentine Cancilleri
    • M. Tricia (Thomas) Benton
    • Mlle Jane Tild
    • Dr. Evelyn Veach

When a civil or military title is used with the surname alone, it is spelled out. When the full name is used, the title is abbreviated.

The military now uses all capitals and no periods to abbreviate titles. However, the conventional spelling of military titles is still used in most forms of civilian writing. Notice that there is a space after the first period in an abbreviated title.

The titles Reverend and Honorable are spelled out if they are preceded by the. They may also be used with social titles. Reverend is never used with the surname alone, but the title may be abbreviated when used with the person’s full name.

Titles After Names. Titles, degrees, affiliations, or the designation Jr. (junior), Sr. (senior), or II, III (or 2d, 3d) following a person’s name are considered part of that name. While the abbreviations Jr. and Sr. are set off from the name by commas, the designations II, III, 2d, or 3d are not set off by commas. These abbreviations are used only with the full name, never just the surname (Mr. Gregory Young, Jr., not Mr. Young, Jr.).

    • Njoki Salumbe, PhD
    • Richard Butzen, LLD
    • Daniel Cronon III, MA
    • Whitney Rune, Sr.

The abbreviation Esq. (esquire) refers to someone who is a lawyer and is never used when another title is given, whether before or after the name.

    • Sue Allen, Esq. not Ms. Sue Allen, Esq.
    • Carl Hanson, Esq. not Carl Hanson, Esq, PhD

Social titles are also dropped if another title is used following the name.

    • Harriet Long, MFA not Miss Harriet Long, MFA

Names with Saint. When Saint precedes the person’s name, it is often abbreviated St., although many prefer to spell the word out.

    • St. Catherine de Sienna or Saint Catherine de Sienna

Saint is generally omitted before the names of apostles, evangelists, and church founders.

    • Matthew
    • John
    • Luke
    • Mark
    • Paul
    • John the Baptist
    • Augustine
    • Jerome

When Saint is used as part of a personal name, follow the style preferred by the individual.

    • Ruth St. Denis
    • Adele St. Claire Hutchins
    • Alfred George Saint-Augustine

Company Names

The following abbreviations are commonly used as part of firm names.

Abbreviations of company names may or may not use periods. Make sure you determine how the company itself prefers to spell its name. Some of the more common abbreviations include the following:

Agencies and Organizations

The names of government agencies, network broadcasting companies, associations, fraternal and service organizations, unions, and other groups are usually abbreviated without periods. However, some publications such as The New York Times still print them with periods. Whichever style you use, be sure you are consistent.

Geographic Terms

In some cases, geographic terms may be abbreviated in more than one way. As always, the key is to be consistent.

Address and State Abbreviations. Address abbreviations may be used with or without periods and may be set in all capitals or in initial capitals only. The U.S. Postal Service recommends using all capitals without periods for address abbreviations. Following is a list of the most common abbreviations used in addresses.

Points of the compass following a street name are used without periods. If they precede the name, periods are used.

    • 147 Eastwood NW
    • 1737 Fifth Street SE
    • 6 N. Michigan
    • 2320 E. Grand

Use the postal zip code abbreviations for states, territories, and the Canadian provinces. The abbreviations are capitalized and contain no punctuation.



Names of Countries. The names of countries should be spelled out whenever possible. When abbreviated, however, periods should be used after each part of the name. There is generally no space after the first period.

For the correct abbreviations for other countries, consult a good dictionary or world atlas.

Place Names. Prefixes such as Fort, Mount, Point, and the like used with geographic names should not be abbreviated unless space must be saved in the text.

Many grammarians make an exception for names beginning with Saint and abbreviate the prefix in all cases. However, the prefixes San and Santa are not abbreviated.

Points of the Compass. The following symbols are used to abbreviate points of the compass.

    • N,S,E,W
    • NE, SE, NW, SW
    • S by SE
    • N by NW

Latitude and longitude are never abbreviated when used alone or in non-technical text. In technical notation, the terms are abbreviated without periods, and the compass symbols inserted following the degrees of latitude and longitude.

    • the equatorial latitudes
    • longitude 22° west
    • lat 42°573 N
    • long 90°275 W


Time designations may be abbreviated in more than one way. Remember to be consistent.

Time of Day. Abbreviations that indicate time of day or night may be set in all capitals or lowercase (or as small capitals).

Days of the Week, Months of the Year. The names of the days of the week can be abbreviated in the following ways:

Months of the year are abbreviated as follows:

Years. Accepted abbreviations mark the years before and after the birth of Christ.

The abbreviation AD (anno Domini—means in the year of the Lord) precedes the year.

    • William the Conqueror landed on British shores in AD 1066.

BC (before Christ) follows the year.

    • Alexander the Great died in the summer of 323 BC.

Scholarly Abbreviations

The rules for use of abbreviations in scholarship are widely agreed upon and include the following:

  1. Abbreviations should be kept out of the body of the text as much as possible, except in technical matters.

  2. Abbreviations such as e.g., i.e., and etc. should be used primarily in parenthetical material.

  3. Scholarly abbreviations such as ibid., cf., s.v., and op. cit. should be used only in footnotes, bibliographical material, and general notes to the text.

Following is a partial list of some of the more familiar scholarly abbreviations. For a complete list, consult a dictionary, scholarly handbook, or more detailed grammar text.


Abbreviations for units of measure are the same whether the unit is singular or plural.

English Measure. The abbreviations for length, area, and volume are followed by periods in nonscientific writing. The abbreviations are as follows:

Abbreviations for weight and capacity reflect the complicated English system of measures. There are three systems in use: avoirdupois, the common system; troy, used by jewelers; and apothecaries’ measure. Although the metric system is being adopted in the United States, these other systems are still in use. The abbreviations are as follows:

English abbreviations for the standard units of time are as follows:

Metric System. The metric system, long used in scientific publications, is gradually becoming the national system of weights and measures. The basic units of measure are the liter, gram, and meter. The following abbreviations are used with metric measurements:

Science and Technology

The International System of Units (SI) is generally used by scientists around the world to label measurements. SI is roughly equivalent to the metric system. In some cases, however, the method of forming abbreviations differs among the various disciplines of science. For a full listing of scientific abbreviations, consult a technical handbook or scientific style book.

Following are the seven fundamental SI units, termed base units, that serve as the foundation terms in science.

The abbreviations used by various branches of science may or may not be related to the International System. Following is a partial list of the more commonly used abbreviations. Notice that they are set without periods.

Commercial Abbreviations

Abbreviations used in business and commerce follow a varied style. The most commonly used abbreviations and their accepted styles are given here.

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