The podictionary word for today is moniker:  The Merriam Webster Unabridged online dictionary tells me that the etymology of moniker is unknown.  But when I turn to the American Heritage Dictionary I’m told that moniker is probably from Shelta, which they go on to tell me is a sort of secret slang that street people in England used to use where words were developed by taking a Gaelic word and reversing its pronunciation. 

In this moniker would be related by various translations and reversals to our word name, which makes some sense.  But the website Etymonline, although it agrees with the street people part, links moniker to monk as might live in a monastery which has a somewhat different etymology than name.  It becomes clear that things are unclear when I look at the OED draft 2002 entry for moniker that says
Origin uncertain.

Various possible origins have been suggested, such as that the word arises from back-slang for EKE-NAME [that's where nickname came from]
or that it represents spec. use of MONARCH or MONOGRAM perhaps blended with SIGNATURE [both of these are more in line with the monk idea]

I’d think that the OED 2002 entry would be pretty up to date.  Although the OED doesn’t say so the idea that it came from the slang of London or English street people is supported with it’s first citation.  One of the guys who founded the humor magazine punch was a guy named Henry Mayhew and during the 1840s he took on a project to interview and write about the underclass in London.  Mayhew was born the same year as Charles Dickens, 1812, so Dickens would have been reading Mayhew’s non fiction accounts of these people as he was writing his fictional accounts. 

So you might think of these two guys as twin forces for social justice in Victorian England.  It was in one of Mayhew’s pieces that the word moniker first appears, and he is very specific in letting readers know that this is part of the slang of the people he is studying.  In this particular case he has subdivided the groups down to a class of people he calls patterers and I guess they were itinerant street vendors called patterers because they kept up a constant patter in trying to sell their wares. 

Mayhew’s articles from the newspaper the Morning Chronicle were later collected into a book called London Labor and the London Poor.  It still makes interesting reading and the full text is available on line.  But if you go looking for it remember to spell labor with a U, the British way.