protactic
/prə(ʊ)ˈtaktɪk/rare
adjective
1Placed before, in front of, or at the beginning of something.
2Of or relating to a protasis; appearing only in a protasis.
Origin
Early 19th century; earliest use found in Noah Webster (1758–1843), lexicographer. From pro- + tactic, after Hellenistic Greek προτακτικός placed in front, used as a prefix.