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Meaning of motherboard

moth•er•board

Pronunciation: (mu'ur-bôrd", -bōrd"), [key]
— n. Computers.
  1. a rigid, slotted board upon which other boards that contain the basic circuitry of a computer or of a computer component can be mounted. Cf.(def. 14).
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.