What is an expansion slot

What is the definition of a Slot ? -AT Internet Glossary slot is phrasal verb​​ slotted in; slotting in; slots in informal : to find a place for in a schedule, plan, etc I can slot you in at 2 slot wings Where does the verb slot come from? The earliest known use of the verb slot is in the mid 1500s OED's earliest evidence for slot is from 1563, in the writing

slot machine monitor slot · ​ a long, narrow opening, into which you put or fit something to put some coins in the slot see also mail slot · ​ a position, a time or an