A pawn that is not opposed by an enemy pawn either on its own file or adjacent files.
ECHESSPEDIA
Quotes of the Day
When you see a good move, look for a better one
Emanuel Lasker
Chess is a scientific game and its literature ought to be placed on the basis of the strictest truthfulness, which is the foundation of all scientific research.
W. Steinitz
Time trouble is blunder time.
Alexander Kotov
I am the best player in the world, and I am here to prove it.
Robert Fischer 1971
If the 12th game (from the match Carlsen-Karjakin)… were a restaurant dish, I would send it back to the chef.
Nigel Short 2016