building block n. 1. A block used as a building material, especially a cinder block. 2. A small wooden or plastic cube used as a building toy. 3. A basic element or part of something: Amino acids are the building blocks of proteins.
building blockn.1. A block used as a building material, especially a cinder block.2. A small wooden or plastic cube used as a building toy.3. A basic element or part of something: Amino acids are the building blocks of proteins.