net
罔 centers on a net: a mesh structure used to catch or trap things. The meaning is concrete and straightforward.
罔 is a pictograph of a net, with the outer enclosure representing the frame and the inner 亡 suggesting the mesh or emptiness. The exact historical development is uncertain.
The outer shape 冂 frames a net, and inside 亡 looks like threads woven together. Picture a net stretched across a frame, ready to catch something.
For モウ, imagine a fisherman mowing through the water with a net: mow -> モウ, and the net scoops up the catch.
to study and not think is a waste; learning without thinking is useless
deception; defrauding someone; fooling someone; swindling; false pretences
slander