A brickwall is a solid and impenetrable structure, which means that its antonyms must be words that convey ideas of permeability, flexibility or weakness. Some of the antonyms for brickwall are porous, penetrable, flimsy, malleable, pliable, yielding, weak or breakable. These words denote either a lack of strength or rigidity, or a capacity to be breached, bent or molded in some way. For example, a porous wall allows liquids or gases to pass through, while a penetrable wall can be breached by force. Similarly, a malleable or pliable material can be shaped or molded, while a weak or breakable one can be easily damaged or destroyed.