Credulity

noun/kɹɪˈduːlɪti/psychology

Definition

A tendency to be too ready to believe that something is real or true.

Etymology

Inherited from Middle English credulite (“faith, belief”), borrowed from Middle French credulité (French crédulité), from Latin crēdulitās. Corresponding to credulous +‎ -ity (compare credulosity).

Synonyms

credulosity, credulousness, gullibility, naivety

In a sentence

Her credulity made her an easy mark for vendor promises.