Use the following general guidelines for forming and using plurals. To find out how to form the plural of a particular word, or for information about whether to use the singular or plural form of a particular word, see Alphabetical list of terms or consult a dictionary.



To form the plural of an abbreviation, an acronym, or a number, add a lowercase s without an apostrophe.

If an acronym already represents a plural noun, don’t add an s.

Note: To refer to more than one FAQ document or section, add the appropriate noun after FAQ and make the noun plural—for example, FAQ articles. Follow this guideline for other plural acronyms when you need to refer to more than one instance of them.

CPUs, APIs, IDs, OSs, the 1990s, 0s and 1s

frequently asked questions (FAQ)

To form the plural of a single letter or a symbol, add an apostrophe and a lowercase s.

x’s, #’s

Abbreviated units of measure are both singular and plural; no s is necessary.

5 mm, 20 in., 20 min

Don’t use (s), /s, (es), or /es at the end of a word to indicate the possibility of more than one item, and don’t combine the singular and plural forms of a verb, such as is/are. Use the singular form or the plural form, use both forms joined by a conjunction, or use the phrase one or more.


Close any application that is open.

Close any applications that are open.

Don’t use:

Close any application(s) that is/are open.