Platelets and ribbons of monolayer molybdenum disulfide ((Formula presented.)) exhibit characteristic electronic states along the edges, which tend to decouple from the extended states in the interior of the 2D extended structure. Under sulfur excess specifically triangular platelets are formed, which exhibit 1D extended electronic states with a pronounced catalytic activity along the edges. The present density-functional-based investigation shows that very similar electronic states occur also along the edges of holes inside an otherwise perfect, extended (Formula presented.) monolayer. For triangular defects, the edge states can delocalize around the hole. Density functional molecular dynamics simulations on 150 different nanoscale defect geometries and termination variants prove the high structural stability of hole defects in (Formula presented.) against further reconstructions and a thermodynamic propensity to participate in sulfur exchange reactions.