building block
From Longman Dictionary of Contemporary EnglishRelated topics: Toysbuilding blockˈbuilding ˌblock noun [countable] 1 DHTa block of wood or plastic for young children to build things with2 → building blocksExamples from the Corpusbuilding block• This will be the foundation building block of your new career.• How does a person not lose him or herself when he or she dissipates such a powerful building block of humanity?