(a plant with) an orange root, used as a vegetable

lure, inducement

something that produces an effect, that makes something happen

agent, originator

(of facts, evidence etc) convincing; removing all doubt

definite, final

that which incites or encourages a person

lure, inducement

a cause or reason for doing something

reason, purpose

a place or reason from which something starts

cause, basis

the starting point (of a river); a place or person from which something comes or is got; original documents etc for an academic study

beginning; point of supply

that cannot be disagreed with

definite, final