thx a lot Aristotle for your "_minimalistic_" reply :)
update: second even shorter line with code from dakkar

< file tr [:blank:],[:punct:] '\n'  | sort -fu
< file tr -cs '[:alnum:]' '\n'|sort -fu
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is exactly what i was looking for!!!
never saw the file redirector < on the beginning of a shell command, i use it for things like:

mail -s "test" person@what_ever.org < file
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