free soil
/ˌfriː ˈsɔɪl/US Politics. Now historical
noun
Territory in which slaveholding is prohibited; an example of this. Chiefly with reference to the views and activities of the Free Soil party.
adjective
Of or relating to (advocacy of) the prohibition of slavery. Especially in the name of or with reference to the Free Soil Party (active 1848–54), which campaigned on the platform that slavery should not be permitted in United States territory.
Origin
Mid 19th century; earliest use found in Subterranean & Working Man's Advocate. From free + soil.