1.Definition: (of persons) lacking art or knowledge

Related Adjective(s):uncultivated, uncultured

2.Definition: characterized by an inability to mask your feelings; not devious

Related Adjective(s):ingenuous

3.Definition: showing lack of art

"An artless translation"

4.Definition: simple and natural; without cunning or deceit

"An artless manner", "Artless elegance"