Definition of "building block" []

• A block used as a building material, especially a cinder block. (noun)
• A small wooden or plastic cube used as a building toy. (noun)
• A basic element or part of something: Amino acids are the building blocks of proteins. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Dioxin, along with pesticides, insecticides, and plasticizers such as bisphenol A, or BPA, a plastics building block used in everything from safety helmets, dental sealants, and eyeglass lenses to everyday food packaging, are what are also known as endocrine disruptors, a group of environmental contaminants that can affect our immune system and our resistance to disease in another particularly insidious way—and in particularly small doses—by disrupting our bodies’ natural hormonal signals."