These rules apply to NOUNS only. For the rules on possessive pronouns, see this post: It's your day to master tricky possessives.
|photo by Jade, morguefile.com|
Singular nounsTo indicate ownership, add an apostrophe and S to singular nouns (no matter what the ending consonant) Some examples are below.
Some style guides make an exception for certain Greek names ending in S: Jesus' life, Demosthenes' pebbles. If you chose to do this, be consistent.
Plural nounsFirst, correctly form the plural.
~Most simply take an S (including names that end with a Y)
~Words and names ending with a sibilant sound such as CH, S, SH, X or Z take an ES ending
~Many common nouns ending in Y take an IES ending
~Some semi-irregular nouns will change the final consonant and take an ES
~Certain Latin words will switch from IS to ES
~Irregular nouns will mutate, including some Latin, Greek, and French words.
When in doubt, look it up. Here's a useful list of oddball plural forms.
With plural nouns ending in s, indicate ownership by adding an apostrophe alone.
For irregular plurals that don't end in an S, indicate ownership by adding an apostrophe and an S (just like a singular noun).
Some examples are below.
With a simple ending:
girls' first win
With a sibilant ending:
churches' service times
Y ending common nouns:
(loaf) loaves' ingredients
(wife) wives' opinions
(elf) elves' fortress
(matrix) matrices' origins
Latin end-vowel changers:
(crisis) crises' causes
(parenthesis) parentheses' color
(oasis) oases' merchants
(mouse) mice's cages
(goose) geese's nests
(ox) oxen's stalls
(child) children's menu
(man) men's restroom
(medium) media's constraints
(curriculum) curricula's format
(fungus) fungi's characteristics
(beau) beaux's names and numbers
Note: If you struggle with apostrophes, avoid giving characters first names ending in s (like Alexis or Joss) or last names ending in s, sh, ch, x or z (like Robbins, Marsh, Koch, Leax, Lopez). You'll eliminate many headaches and confusion for yourself.
Mixed groupsGenerally you want the same number of apostrophes as items possessed.
For shared ownership, one apostrophe:
Jane and Jordan's new apartment
Frost and Wright's collection
Similar items that are owned (or were created) by separate people or entities take multiple apostrophes:
Kimball's and Jones's books on the Civil War
Girls' and boys' locker rooms
Owen's and the Mosses' cars
With mixed combinations (like a single person and a couple), make the number of apostrophes match the number of items:
The tree fell on Tim's and Dave and Becky's houses.
Two houses, two apostrophes.
Probably the most common errors occur with names ending in S where it's unclear whether you're dealing with one person or a group. You can go to Ross's house or the Rosses' house, but please don't ever talk about Ross' house. It's just confusing.
Which of these things tend to trip you up?