Why are nicknames called "nicknames"?

Where did this term originate from? According to Etymonline.com, it originates from O.E. eaca, which means to "increase". However, I can't see how the "n" got stuck in there too.

Does anyone have any relevant information?

Solution 1:

Metanalysis strikes again.

The regular outcome of OE eaca would be ick, as in ickname. At some point an ickname became reanalyzed as a nickname, and that's how the word has reached us today.

Solution 2:

It's metanalysis from an ickname to a nickname.

Solution 3:

Please advise if the following erred, but it helped me to naturalise or rationalise the etymology. Each indent signifies a response to an earlier post; I omit each post's usernames for readability.

[Source:] The best one I can think of off the top of my head goes back to before last names where a thing, so people would sometimes use "eke" (pronounced like "eek") names, meaning other name. Over time, people referring to "an eke name" was eventually morphed into "a nekename," which is where we get the word nickname.

In Chaucer's Middle English, "eke" is usually translated as "also", so it would've been an "also name". eg. in the Miller's Tale, we have:

The Miller was a stout carl, for the nones,.
Ful big he was of braun, and eek of bones;

Which translates, roughly:

The Miller was a tough bloke for this occasion
He was big in his brawn, and also in his bones