Rebracketing, also known as resegmentation or metanalysis, happens when words are split into parts different from the way they were originally. It is common in languages all over the world, and it is one of the ways in which new words are formed.
To understand rebracketing, consider the word "metanalysis". The understanding of this word is naturally "meta + analysis", but it could also be understood as either "met + analysis" or "meta - nalysis". It is this ambiguity that leads to rebracketing.
Examples
Apron
One of the most famous -- indeed, the quintessential -- examples of rebracketing is the word 'apron'. Although the modern word is 'apron', it was actually 'napron' or 'naperon' in Middle English, as derived from French napperon (meaning doily or small tablecloth).
Through the process of rebracketing, the phrase "a napron" gradually became understood as "an apron".
Alcoholic
The word 'alcoholic' contains not one, but two, examples of rebracketing -- a testament to the productivity of rebracketing as a process that creates new words!
The now-English 'alcohol' actually came from Arabic al-kuḥl, where al means 'the' and kuhl means 'powder'. We can thus say that the original division of 'alcohol' is 'al+cohol'.
However, the word has now been divided into 'alco+(h)ol' -- as shown by the emergence of words like 'methan-ol' or 'xylit-ol' (which are chemical terms referring to specific alcohols).
'Alcoholic' itself has also undergone rebracketing; 'alcohol+ic' is now understood as 'alco-holic', where the new suffix 'holic' now suggests obsession or addiction. This gives rise to words like "workaholic", "shopaholic", "chocoholic", and more.
Can you think of more rebracketed words?