APA Style: Abbreviations

A recent article summarizing previous data from 110 manuscripts submitted to the Research in the Schools journal (Onwuegbuzie, Combs, Slate, & Frels, 2010) shows that APA style deviations related to the use of abbreviations and acronyms were found in 41.82% of the manuscripts. Perhaps because using abbreviations in writing comes so intuitively to us, a lot of people don’t give much thought to the fact that the publication manual of the American Psychological Association (APA, 2009) has some specific requirements when it comes to abbreviations. And while the rules governing the use of abbreviations may seem like just another bunch of the innumerable guidelines in the manual, it doesn’t take long to realize that they are actually logical and easy to follow.

Using Abbreviations: The Basics

Abbreviations are generally useful for long, technical terms in scientific writing and their use is justified if they add to the clarity of the text. The rule of thumb is that expressions should be spelled out the first time they are mentioned in the text followed by the abbreviation in parentheses, and then abbreviated on all other occasions. However, when deciding whether to abbreviate or not a certain term, keep in mind that abbreviations that are introduced on a first mention in the text and appear less than 3 times thereafter are not advised. This is especially true for longer texts, when spelling out the term each time can be less confusing to the reader.

Some abbreviations don’t need an explanation if they appear as word entries in the Merriam-Webster’s Collegiate Dictionary (2005):

For example: REM, ESP, AIDS, HIV, NADP, ACTH.

Others appear often in journals, and although they are probably familiar to many readers, they nonetheless should be explained at first use: e.g., reaction time (RT), conditional stimulus (CS), short-term memory (STM).

To form the plural of abbreviations, just add s at the end:

For example: IQs, RTs, Eds.

However, this rule does not apply to units of measurement (e.g., 45 m, 23 kg; see below)

Units of Measurement

Units of measurement are normally abbreviated when they are accompanied by a numerical value (e.g., 5 cm, 36 min, 12 h). However, do not repeat the abbreviation when expressing multiple amounts (e.g., 12-15, 20-23 and 27-30 kHz),

Also, do not place a period after abbreviated measurements. The only exception to this rule is in. (inch), in order to avoid confusion.

The following units of time should not be abbreviated when accompanied by a numerical value: day, week, month, year.

On the other hand- hour (hr), minute (min), millisecond (ms), nanosecond (ns) and second (s) should be abbreviated.

Latin Abbreviations

There are several Latin abbreviations that appear only in parenthetical material:

c.f. – compare                                     i.e. – that is

e.g. – for example                               viz. – namely

etc. – and so forth                              vs. – versus

However, please note that when used in non-parenthetical material, you should use the English translation of the Latin terms. One exception to this rule is et al., which can be used both in parentheses and in the text.

Abbreviations in the Reference List

There are some abbreviations that appear in the reference list and/or in citations (see Table 1):

Table 1

Abreviations in the Reference List:

Abbreviation Book or publication part
ed. edition
Rev. ed. Revised edition
2nd ed. second edition
Ed. (Eds.) Editor (Еditors)
Trans. Translator(s)
n.d. no date
p. (pp.) page (pages)
Vol. Volume (as in Volume 4)
Vols. Volumes (as in Volumes 1-4)
No. Number
Pt. Part
Tech. Rep. Technical Report
Suppl. Supplement

Note: Adapted from APA, 2009.

Please note that some of them are capitalized while others are not.




American Psychological Association. (2009). Publication manual of the American Psychological Association (6th ed.). Washington DC: Author.

Merriam-Webster’s collegiate dictionary (11th ed.). (2005). Springfield, MA: Merriam-Webster.

Onwuegbuzie, A. J., Combs, J. P., Slate, J. R., & Frels, R. K. (2010). Editorial: Evidence-based guidelines for avoiding the most common APA errors in journal article submissions. Research in the Schools, 16(2), ix–xxxvi.



Martin Vasilev is an Editor in JEPS. He is a final year undergraduate student of Psychology at the University of Sofia, Bulgaria, and the author of some of the most popular posts at the JEPS Bulletin (see for example, his post on writing literature reviews, which was reprinted in the MBA Edge, a magazine for Malaysian prospective postgraduate students).

Martin Vasilev

Martin Vasilev

Martin Vasilev is a final year undergraduate student of Psychology at the University of Sofia, Bulgaria, and the author of some of the most popular posts on JEPS Bulletin (see for example, his post on the most common mistakes in APA style was the most read in the JEPS Bulletin in 2013 and his post on writing literature reviews, which was reprinted in the MBA Edge, a magazine for prospective postgraduate students in Malaysia)

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  • Pascal

    c.f. should be cf.