Core  —n. 1 horny central part of certain fruits, containing the seeds. 2 central or most important part of anything (also attrib.: core curriculum). 3 inner central region of the earth. 4 part of a nuclear reactor containing fissile material. 5 hist. Structural unit in a computer, storing one bit of data (see *bit4). 6 inner strand of an electric cable. 7 piece of soft iron forming the centre of an electromagnet or induction coil. —v. (-ring) remove the core from.  corer n. [origin unknown]