ˈ ̷ ̷ˌ ̷ ̷ noun
1.
a. : a rhizomatous underground part of a plant
b. : a stock for grafting consisting of a root or a piece of root ; broadly : stock
2. : hydrorhiza
3. : a source of offshoots : origin
going back to one of the rootstocks of economic thought — Times Literary Supplement