noun

1. A gullible person; someone easily fooled or tricked.

adjective

1. Easily deceived or duped; naive, easily cheated or fooled.

   “Andrew is so gullible, the way he still believes in Santa Claus, the Easter Bunny, the Tooth Fairy, and the Sandman at the age of fourteen.”

Synonyms: fleeceable, green, naif, naive