A male householder or lodger with his own separate fireplace on which a pot could be boiled, which qualified him to vote in a parliamentary election in some English boroughs before the 1832 Reform Act.
This system of determining the electorate was one of the abuses criticized by electoral reformers in the early 19th century.
Early 18th century; earliest use found in Original Journals of the House of Commons. From pot + wall + -er. Compare earlier pot-walling.