Lewis Short
centrum (noun N) = κέντρον: (a prickle, sharp point).
* Centrum circini, the stationary foot of the compasses, around which the other is carried in making a circle, Vitr. 3, 1; 9, 5.—Hence
* Meton.
* The middle point of a circle, the centre, Vitr. 3, 1; 9, 1; Plin. 2, 15, 13, § 63; 2, 19, 17, § 81 et saep.—In plur.: solis terraeque centra,Plin. 18, 29, 69, § 281 (in Cic. Tusc. 1, 17, 40, used as a Greek word).
* A kernel, a hard knot in the interior of wood, precious stones, etc., Plin. 16, 39, 76, § 198; 37, 2, 10, § 28; 37, 9, 39, § 120 al.
Charlton T. Lewis, Charles Short, A Latin Dictionary