"structuralism is a difficult concept"

• a plan or intention

  "the centre has kept firmly to its original concept"

• an idea or invention to help sell or publicize a commodity

  "a new concept in corporate hospitality"

• (of a car or other vehicle) produced as an experimental model to test the viability of innovative design features

  "a concept car for next month's Geneva motor show"

• an idea or mental image which corresponds to some distinct entity or class of entities, or to its essential features, or determines the application of a term (especially a predicate), and thus plays a part in the use of reason or language