How a napron became an apron
When you speak, you don't pause between words. Said aloud, a napron and an apron sound almost the same, and a listener has to decide where one word ends and the next begins. In English that decision has sometimes gone the other way, and the new version stuck.
Linguists call this rebracketing, or metanalysis: a word or phrase gets divided differently from the way it was built. The clearest English examples involve the articles a and an, because the n can belong to either side.
The n that moved
Apron came into English from French as napron, a small piece of cloth, so people said a napron. Heard as an apron, the word lost its first letter, and apron is what we say today. The adder, a snake, went the same way: Middle English a naddre was taken for an addre.
Umpire took longer. It comes from the Old French nonper, not equal, for someone asked to settle a dispute between two people. English had noumper by around 1350, and in 1426 or 1427 it was still written a noounpier. The first spelling without the n appears around 1440, and by about 1475 an oumper had taken over.
The n could also move the other way. An ekename, an extra name, was recorded as early as 1303, from an Old English word meaning also. By the 15th century people were saying a nekename, which became nickname. Newt followed the same path, from Middle English an eute to a neute.
English isn't alone. In Old French, une norenge, an orange, was heard as une orenge, and the fruit lost its n there too.
Each of these words is a small fossil of a moment when someone heard a phrase differently and nobody corrected them. Once enough people say the new form, it isn't a mistake any more. It's the word.
What did Middle English speakers say before an apron?
Speech has no spaces, so an n can slip between a or an and the noun beside it. That is how a napron became an apron.
