组成部分；构成材料
Merriam-Webster Online Dictionary
building block (noun) a unit of construction or composition , especially something essential on which a larger entity is based
Merriam-Webster Online Thesaurus
building block (noun)one of the parts that make up a whole
SYNONYMS:
building block, component, constituent, factor, ingredient, memberRELATED WORDS:
basis, part and parcel; detail, item, particular, point; aspect, characteristic, facet, feature, trait; division, fragment, particle, partition, piece, portion, section, sector, segment; subcomponentNEAR ANTONYMS:
aggregate, composite, compound, mass; entirety, sum, summation, total, totality; admixture, amalgam, amalgamation, blend, combination, intermixture, mix, mixture