Supercede v Supersede (Merriam Webster v OED)
Update: apparently it’s supersede – no contest.
According to the Shorter OED (5th Edition):
“supersede: Also (earlier) -cede L15. [Old French superceder, later -seder, from Latin supersedere (in medieval Latin freq. -cedere) set above, be superior to, refrain from, omit formed as SUPER- +sedere sit.]”
Merriam Webster (online) asserts:
“Supercede has occurred as a spelling variant of supersede since the 17th century, and it is common in current published writing. It continues, however, to be widely regarded as an error.”
So, both prefer -seded, and this is closer to the root. MW admits common usage then sort-of asserts -cede to be an error. OED just says -cede is a variant (not an error).
Microsoft Word, by the way, marks it as an error.
[Update: Merriam corrected]
Brendan Scott's Weblog 
I think the reason I always want to spell it “supercede” is because I think of it pairing with “cede.”
Excellent read, thank you! I’m commenting on this is because I’m not a bot and I can sympathize with receiving a bunch of spam comments. And to thank you for the info of course.
Google Keywords “supersede vs supercede” (without quotes) brought me here, very nice.
I don’t know why we have adhere to usages that are largely accidental in their origin. If we have precede it is logical to use supercede.
That is precisely my reasoning Patrick Carroll. “To cede” and “precede” are both correct, so why would supercede be incorrect?
That assumes precede and supersede have the same etymology, which doesn’t seem to be the case. Precede is from cedere “to go” and supersede is from sedere “to sit”. As they’re different it makes sense the spellings remain different!
As well as, secede.
User “An” is correct above (pun not intended). I studied Latin and English at school and as a “Grammar Nazi” of note, I am devastated that the “C” has been superSeded. *sheds a tear* :-(
Fantastic explanation! Really helpful.
Yes thank you. I have always used supercede…. but I may have to mend my ways….
supersede = replace; supercede = precede
From the Latin “sedeo/sedere” [ = to sit on top of], not “cedo/ceders” [= to walk (over)].
If Thai is correct, then may I suggest that the article ‘s “Update” line be revised?
“So, both prefer -seded, and this is closer to the root.”
Not true. The Latin is misreported. The Latin verb in the root of English supercede is cedere, meaning ‘yield to’, ‘give way to’. Sedere means ‘to sit. “
According to the Shorter OED, cedere is a medieval spelling.
If supersede means “replace” – then sede means “to yield”, “give in”, or “grant”, right??? NO NO NO
There is no definition of “sede” in any Websters or Oxford – both recognize “cede” as “to yield”, “give in”, or “grant”.
Look up the root of the word “sedentary” – Latin for “sit” or “stay in one place” – definitely NOT the action of moving above or replacing!
Like the altering of political terms in the mid 2000s – it seems like “supersede” is more “making it up as you go along”.
Please consider removing the “apparently it’s supersede – no contest.” “Update” comment at the top. As stated by Billy Bones – with correct Latin translation and hopefully backed up by clear uniformity evidence I have presented, the “no contest” descriptor should cede the clear win to “supercede”. Spell checkers CAN be wrong – dictionaries too.
Critical thinking – it still matters. Spelling – it still matters.
Ok – not granting, but replacing or overtaking. Most common is supersede –
I do promise that 1983 Webster’s lists them as interchangeable.
root of sit or not moving – verb vs adjective – grrrrrr ha!
I concede…