The quality or state of being currish; base, cowardly, or contemptible behavior or character.
From 'currish' (adjective) plus the noun-forming suffix '-ness,' which creates abstract nouns describing qualities or states.
The suffix '-ness' is so productive in English that you can add it to almost any adjective to make an abstract noun—'currishness' follows this pattern, though it's now archaic enough that most English speakers wouldn't recognize it.
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