a connection in a computer, especially a personal computer, to which a new board or card can be added to expand the computer's capabilities.
Origin of expansion slot
First recorded in 1980–85
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for expansion slot
a physical electronic interface provided in a computer system to enable extra facilities to be added easily at a later date
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012