Mid 17th century; earliest use found in Thomas Johnson (d. 1644), apothecary and soldier. From (i) Middle French, French †substantifique essential, vital.
Definition of substantific in US English:
substantific
adjectiveˌsʌbst(ə)nˈtɪfɪk
That produces substance; that substantifies.
Origin
Mid 17th century; earliest use found in Thomas Johnson (d. 1644), apothecary and soldier. From (i) Middle French, French † substantifique essential, vital.