building blockbuilding block
a fundamental element, fact, idea, etc. upon which something is built, developed, maintained, etc.: usually used in pl.
Origin of building blockby analogy with a block as of cement used as a unit in the construction of a building, barrier, and the like
- A block used as a building material, especially a cinder block.
- A small wooden or plastic cube used as a building toy.
- A basic element or part of something: Amino acids are the building blocks of proteins.