Guileless, a.
Free from guile; artless. -- Guile"less*ly, adv. Guile"less*ness, n.
Shades of meaning
Fernald has no entry of its own for guileless; he lists it under candid, innocent, pure.
Where he writes about it:
On the other hand, artless, guileless, naive, simple, and unsophisticated express the goodness which comes from want of the knowledge or thought of evil. — from candid
Synonyms
candidinnocentpureaboveboardabsoluteartlessblamelesschasteclassicclassicalcleanclearcontinentfairfaultlessfrankgenuineguiltlessharmlessholyhonestimmaculateimpartialincorruptingenuousinnocuousinnoxiousinoffensivemerenaiveopenperfectrealrightrighteoussheersimplesinceresinlessspotlessstainlessstraightforwardtransparenttruetruthfulunadulteratedunbiasedunblemisheduncorruptedundefiledunmingledunmixedunpollutedunprejudicedunreservedunsophisticatedunspottedunstainedunsullieduntainteduntarnisheduprightvirtuous