In this paper, we introduce the concepts of a 2-outer-independent semitotal dominating set and the corresponding parameter 2-outer-independent semitotal domination number of a graph. We determine bounds (or exact values) of the 2-outer-independent semitotal domination number of some graphs. Also, we show that for graphs without isolated vertices, the 2-outer-independent semitotal domination and 2-outer-independent domination are equivalent concepts.

outer-independent, semitotal domination, independence number, complementary prism, lexicographic product.