simple

[1]

simpleton

adj.

[1]	uncomplicated , plain , uninvolved , unsophisticated , understandable , intelligible , (easily) understood , comprehensible , clear , lucid , straightforward , easy , elementary , basic
[2]	plain , unadorned , undecorated , unembellished , basic , fundamental , elementary , elemental , mere , unostentatious , unassuming , unpretentious , modest , classic , uncluttered , stark , clean , severe , austere , Spartan , homely , unvarnished , naked , honest
[3]	sincere , frank , candid , open , unaffected , uncomplicated , unpretentious , straightforward , above-board , simple-hearted , uncontrived , direct , upright , square , forthright , four-square , righteous , honest , naive , guileless , artless , undesigning , childlike , ingenuous , unsophisticated , innocent , green
[4]	unsophisticated , elementary , uncomplicated , naive , slow , unproblematic , slow-witted , stupid , thick , thickheaded , simple-minded , feeble-minded , oafish , bovine , dense , obtuse , dull , dull-witted , witless , halfwitted , brainless , backward , imbecilic/(Mainly Brit) imbecile , cretinous , (Colloq) dumb , moronic
[5]	lowly , bare , mere , humble , inferior , mean , base , subservient , common , subordinate
[6]	childlike , wide-eyed , round-eyed , dewy-eyed
[7]	dim-witted , simple-minded
[8]	unsubdivided