Meaning of knopper gall in English:

knopper gall

Pronunciation /ˈnɒpə/

noun

  • A hard, irregular umbrella-like gall which forms on an oak acorn in response to the developing larva of a gall wasp.

    The wasp is Andricus quercuscalicis, family Cynipidae

Origin

Late 19th century knopper from German Knopper ‘gall’.