guileless (adj.)

• artless
• bluff
• blunt
• candid
• childlike
• confiding
• credulous
• dependent
• direct
• frank
• ingenuous
• innocent
• naive
• open
• openhearted
• outspoken
• plain
• reliant
• simple
• sincere
• single-minded
• trustful
• trusting
• trusty
• unaffected
• unassuming
• undisguised
• unfeigned
• unflattering
• unguarded
• unpretending
• unreserved
• unschooled
• unsophisticated
• unstudied
• unsuspecting
• unsuspicious
• untrimmed
• untutored
• unvarnished
• unwary