Apostrophes are mainly used to show the possessive case of nouns and indefinite pronouns in accordance with the Chicago Manual of Style.
To show possession according to the rules for singulars and plurals in CBE, 5th ed.
Possessive is permitted with inanimate objects:
We determined in four vertically displaced areas the spatial sensitivity distribution of the two CH-cells' ipsilateral reception fields.
To pluralize single letters, both capital and lowercase. (This is done to avoid confusion with other symbols that might be used.)
On this graph, the y's and x's represent...
To pluralize a single-digit numeral. Plurals of numerals greater than 9 have no apostrophe, only "s" added.
3's look like 8's.
results are expressed in 100s.
To show possession of compound terms.
physician-in-chief's decision
To show joint possession for proper names of organizations/businesses.
To pluralize an abbreviation, acronym, or year. Use a lowercase "s".
EEGs, RBCs, during the 1980s.
For verb contractions; instead, write contractions out. E.g., change "don't" to "do not."
With possessive pronouns: his, hers, its, theirs, whose, etc.
With eponyms (consult current editions of Stedman's and/or Webster's Collegiate, latest edition)
Raymand disease
Martan syndrome
Stanford-Binet scale
Newman-Keuls test
Wilcoxon rank sum test
Do not use an apostrophe when a prime symbol is meant. The proper prime symbol is located in the Special Characters menu in Stickit; alternatively, you can use the «prime» code.
last edited 07/25/03