Meaning of side card

side' card"

Pronunciation: [key]
— Cards. Cards.
  1. the highest card in a hand that is not part of a scoring combination, as not being one of a pair, three of a kind, etc., and that serves to determine by its denomination the higher ranking of two otherwise equal hands.
  2. a card other than a trump; plain card.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.