Source, derivation (6)
I believe the answer is:
origin
I believe this is a double definition.
'source' is the first definition.
(I know that source can be written as origin)
'derivation' is the second definition.
(I know that origin is a type of derivation)
(Other definitions for origin that I've seen before include "Source, root" , "extraction" , "Genesis" , "Where axes cut" , "Place where something begins" .)