What is another word for "simple"?

Roget's Thesaurus (1911) lists these synonyms for "simple": all, away, bait, believing, bigotry, bite, blind, call, catch, chaste, cheese, childish, come, common, commonplace, conclusion, confident, confiding, credo, credulity, credulous, credulousness, cull, cullibility, cully, deceive, deception, delusion, down, dry, dupe, easily, error, fact, fall, father, flat, follow, fool, for.