What does the word core mean?

Usage examples for core

  1. Upper ends that support core board should be bent as shown in Fig. – Taxidermy by Leon Luther Pray
  2. She felt that to the innnermost core of her heart. – Judith of the Cumberlands by Alice MacGowan
  3. She was so beautiful and so rotten at the core that she would be better dead.... – The Vision of Desire by Margaret Pedler