IPA: /ˈruːtstɒk/
KK: /ˈrutˌstɑk/
A part of a plant's root used to grow new plants, often for grafting purposes.
The gardener chose a strong rootstock to ensure the health of the new plant.
Rootstock → The word is formed from "root" (from Old English "wroot", meaning the part of a plant that grows underground) and "stock" (from Old English "stoc", meaning a stem or trunk of a plant). Together, "rootstock" refers to the underground part of a plant that supports the above-ground growth.
Think of the 'root' as the part of the plant that grows underground and 'stock' as the stem that supports it — together, they form the base of a plant.