Small working horse

Wikipedia Word definitions in Wikipedia
Pit Pony is a 1999 CBC television series which tells the story of small-town life in Glace Bay , on the island of Cape Breton , Nova Scotia in 1904. The plot line revolves around the lives of the families of the men and boys who work in the coal mines.

Longman Dictionary of Contemporary English Word definitions in Longman Dictionary of Contemporary English
noun EXAMPLES FROM CORPUS ▪ He had spent his working life down the local pit and drove a pit pony when he first went underground.