1(a). A thing inside which you write notes.<p>Plus the document model used — a mix of different kinds of &quot;cells&quot;  — has a history of being called a &quot;notebook interface&quot; (cf. Mathematica, IPython&#x2F;Jupyter notebook,  <a href="https:&#x2F;&#x2F;www.quora.com&#x2F;What-is-a-notebook-interface-in-programming" rel="nofollow">https:&#x2F;&#x2F;www.quora.com&#x2F;What-is-a-notebook-interface-in-progra...</a>).