Unrefined and Unlettered

Unrefined adjective - Being such as found in nature and not altered by processing or refining.

Unlettered and unrefined are semantically related In some cases you can use "Unlettered" instead an adjective "Unrefined".

Unlettered adjective - Lacking in education or the knowledge gained from books.

Unrefined and unlettered are semantically related in crude topic. Sometimes you can use "Unrefined" instead an adjective "Unlettered", if it concerns topics such as uncultivated, lacking knowledge.