The term 'as a brick thick' is an idiom that means something is very DENSE or solid. This phrase can be used to describe the density of a material, such as a wall or a person's skin. The crossword solutions for this phrase are DENSE (5 letters), OBTUSE (6 letters), ADOBE (5 letters), and LEGO (4 letters). DENSE means having a high concentration of mass in a given volume, while OBTUSE means having a blunt or rounded shape. ADOBE is a type of building material made from clay, sand, and straw, and LEGO is a popular toy made of interlocking plastic bricks. All of these words relate to the phrase 'as a brick thick' in that they all describe something that is very DENSE or solid.