Knopern or Knoppern: How To spell?

The word Knopern is misspelled against Knoppern, a noun meaning "A kind of gall produced by a gallfly on the cup of an acorn, -- used in tanning and dyeing."

Knoppern has double "pp" is mispronounced as "p"
Remember double 'PP' in between the strings kno & ern which should not be misspelled with single 'P'
Wrong Spelling:  kno-p-ern 
Correct Spelling:  kno-pp-ern 
Find more incorrect spellings of Knoppern to spell right way.

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