S: (adj) naive, naif (marked by or showing unaffected simplicity and lack of guile or worldly experience) "a teenager's naive ignorance of life"; "the naive assumption that things can only get better"; "this naive simple creature with wide friendly eyes so eager to believe appearances"
S: (adj) trustful, trusting (inclined to believe or confide readily; full of trust) "great brown eye, true and trustful"- Nordhoff & Hall