gul ‧ li ‧ ble /ˈɡʌləb ə l, ˈɡʌlɪb ə l/ BrE AmE adjective
too ready to believe what other people tell you, so that you are easily tricked:
Plastic replicas of the Greek pottery are sold to gullible tourists.
—gullibility /ˌɡʌləˈbɪləti, ˌɡʌlɪˈbɪləti/ noun [uncountable]