The possessive apostrophe should be easy. Take the words, and ‘s to it. Like this:
This rule will take you a long way, but it’s not always that simple.
Words that already end in an ‘s’
If you are adding the ‘s to a word that already ends in an s it becomes trickier. Now you need to decide if the word ending in ‘s’ is singular or plural. Boss is singular, bosses is plural. Hypothesis is singular, girls is plural.
If it is singular, like ‘boss’ in the example above, follow the usual rule – add the ‘s.
If it is plural, you have to take care. See below:
Hypotheses don’t have friends
Hypotheses don’t have friends, so here’s another illustration:
This is incidentally, a very good example of where it is better to avoid the use of the apostrophe altogether, even when it is grammatically correct. It is much better to say:
- The premise of the hypothesis
- The premises of the hypothesis
- The premise of the hypotheses
- The premises of the hypotheses
Don’t assume that a more sophisticated sentence construction is necessarily better, or will make you look cleverer. Not so. Readability is king.