Mid 19th century; earliest use found in Samuel Taylor Coleridge (1772–1834), poet, critic, and philosopher. From phantom + -atic. Compare French fantomatique.
Definition of phantomatic in US English:
phantomatic
adjectiveˌfantəˈmatɪk
Phantom-like; unreal.
Origin
Mid 19th century; earliest use found in Samuel Taylor Coleridge (1772–1834), poet, critic, and philosopher. From phantom + -atic. Compare French fantomatique.