Junctural metanalysis

Junctural metanalysis is the process by which new words are formed from confusion over the boundaries of words. It is sometimes referred to as "false splitting," "juncture loss," and is a form of back formation.

The most cited examples of junctural metanalysis involve of words which are preceded by the indefinite article ("a" or "an"): some words that began with an initial vowel gained an "n" as speakers came to associate the "n" from the indefinite article ("an") with the word itself. Examples include:
* newt: "an ewt" became "a newt." Ultimately, the word can be traced back to Old English efete (sometimes spelled "eft").
nickname: from "an eke name" ("eke" meaning "little" or "extra").

Conversely, sometimes words which began with an initial "n" lost it through a similar process:
apron: "a napron" became "an apron." "Napron" itself meant "little tablecloth" and is related to the word "napkin."
adder: from "a nadder."
umpire comes to us from the Middle English noumpere, which itself is adopted from the Old French nonper (someone "without peer" who could act as an arbiter of a dispute).
orange: this word lost its initial "n" in translating the Arabic nāranj into Old Italian melarancio (from "mela, "fruit," and arancio, "orange tree"). It can be further traced to the Sanskrit nāraṅgaḥ, which was possibly a Dravidian borrowing. From Old Italian it passed to Old French as pume orenge. It first appears in a Middle English text around 1380.

Junctural metanalysis of a different sort, involving confusion over a final "s" rather than an initial "n", accounts for the word "pea". It was originally the singular Middle English mass noun pease (collective in that it refers not to a single unit, but to an amassing of the vegetable, akin to "corn").

Another example is "helicopter" from Greek `ελικο-πτερον = "[having] rotating wing(s)", but misdivided as "heli-copter", from which came modernisms such as "heli-backpack" and "heliport" and "jetcopter".