罔 originally pictured a hunting net (the modern
网 wǎng descends from it). It then extended figuratively: a net that catches and deceives people → 'to deceive'; what falls through a net → 'nothing, none'. The famous Analects line
学而不思则罔 uses the 'be deluded / caught in a net of confusion' sense. Today
罔 is mostly literary, surviving in fixed phrases like
置若罔闻 ('treat as if heard nothing') and
欺君罔上 ('to deceive the sovereign').
