The quality or state of being boobish; foolishness, silliness, or stupidity exhibited in behavior or character.
From 'boobish' plus the noun-forming suffix '-ness' (Old English '-nes'). This suffix converts adjectives into abstract nouns describing the quality or condition named by the adjective.
The '-ness' suffix is one of English's most prolific—you can attach it to almost any adjective to create a noun: happy→happiness, sad→sadness, boobish→boobishness. It's infinite expressiveness!
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