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Which is correct? For convenience sake, or for convenience's sake, or for convience' sake?
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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:
http://www.worldwidewords.org/qa/qa-app2.htm
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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.

Rick
for convenience' sake......http://en.wikipedia.org/wiki/Apostrophe#Singular nouns_ending_with_an_.22s.22_or.22z.22_sound.......peace.
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I would go for an apostrophe 's' for singular nouns or uncountable nouns, so I go for ' for convenience's sake ', as how we say "for goodness' sake " ; ' for God's sake'; ' for mum's sake ' ' for old times' sake '.

See the distribution of the three forms here:

https://books.google.com/ngrams/graph?content=for+convenience%27+sake%2Cfor+convenience%27s+sake%2Cfor+convenience+sake&year_start=1800&year_end=2000&corpus=15&smoothing=3&share=&direct_url=t1%3B%2Cfor%20convenience%20%27%20sake%3B%2Cc0%3B.t1%3B%2Cfor%20convenience%20%27s%20sake%3B%2Cc0%3B.t1%3B%2Cfor%20convenience%20sake%3B%2Cc0

Wikipedia has this:

Some writers like to reflect standard spoken practice in cases like these with sake: for convenience' sake, for goodness’ sake, for appearance' sake, for compromise’ sake, etc. This punctuation is preferred in major style guides. Others prefer to add ’s: for convenience’s sake.[33] Still others prefer to omit the apostrophe when there is an s sound before sake: for morality’s sake, but for convenience sake.[34]

From https://en.wikipedia.org/wiki/Apostrophe#Singular

CJ