Text formatting and special treatment of particular words

Hi,

when reformatting a text paragraph with gwip it causes some words to
be treated special. Example:


Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumydiam for tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet.

Formatting the paragraph with "gwip" results in

Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumydiam
for tempor invidunt ut labore et dolore magna aliquyam erat, sed diam
voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet
clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit
amet.

This makes sense for programming, but not for plain text. Filetype
is not set BTW. I assumed that some of the formatoptions were
responsible for the recognition of the keywords so I removed all
formatoptions yielding the same result as described.

How can I control this behaviour and remove special treatment of
particular words?

Marco