Would you write Arnold's or Arnolds'?

Answer 1

It depends on what you are trying to say! Let's assume you are referring to a married couple whose last name is "Arnold"

1) [Plural] To simply refer to the two of them, write "the Arnolds' (e.g., "The Arnolds are coming over for dinner.")

2) [Singular possessive] To refer to something belonging to ONE of them, write "Arnold's" (e,.g., "This is Mr Arnold's car.") The same form would bee used for an individual (man) whose FIRST name is Arnold. ("This is Arnold's car.")

3) [Plural possessive] To refer to something belonging to BOTH of them, write "Arnolds'" (e.g., "Have you ever seen the Arnolds' house?")

KEY POINT -- The apostrophe is used to indicate POSSESSION, not to mark something as PLURAL!

GENERAL RULE - To form the possessive of a singular noun you will almost alway simply add - 's. To form the possessive of a PLURAL noun that already has a final "s" used to make it plural (such as "cars', "desks"), simply add an apostrophe at the end.

The main exception to this rule is "irregular" plurals, that is, those formed without the adding of an "s", e.g., common plurals like: children, men, geese. For these, form the possessive by adding "'s" (just as with the singular possessive).

The same rules that apply to common nouns generally apply to personal names. (Which names "break" the "add -'s rule" is debated. One common solution is to simply add it unless the result becomes very awkward and difficult to pronounce because of having too many "s" sounds in a row. Example: possessive for Jesus & Moses would be Jesus' and Moses' NOT Jesus's and Moses's.)