Definition of free stock in English:

free stock

noun

Horticulture
  • A type of rootstock (now chiefly of apple) that will not dwarf or restrict the final size of the tree which is grafted on to it, and is typically grown from seed.

Origin

Mid 17th century; earliest use found in John Evelyn (1620–1706), diarist and writer. After French arbre sur franc.