superstitious adj.

early 13c., "false religious belief; irrational faith in supernatural powers," from Latin superstitionem (nominative superstitio) "prophecy, soothsaying; dread of the supernatural, excessive fear of the gods, religious belief based on fear or ignorance and considered incompatible with truth or reason," literally "a standing over," noun of action from past participle stem of superstare "stand on or over; survive," from super "above" (see super-) + stare "to stand," from PIE root *sta- "to stand, make or be firm."

There are many theories to explain the Latin sense development, but none has yet been generally accepted; de Vaan suggests the sense is "cause to remain in existence." Originally in English especially of religion; sense of "unreasonable notion" is from 1794.