Which is correct? For convenience sake, or for convenience's sake, or for convience' sake?
Hi Anon

As far as I know, many (and possibly most) style guides say that the addition of an apostrophe at the end of words that are spoken with an S sound at the end (such as convenience and goodness) is formally correct. In other words:
- for goodness' sake
- for convenience' sake

However, I believe that many consider the apostrophe to be completely optional.

There is an interesting write-up on this topic here:
I usually try to avoid awkward syntax like that. At least when writing. Instead you can say something like:

For the sake of convenience, ...
You can always say "for the sake of convenience". But I think "for convenience sake" or "for convenience's sake" are both fine.

for convenience' sake......http://en.wikipedia.org/wiki/Apostrophe#Singular nouns_ending_with_an_.22s.22_or.22z.22_sound.......peace.