I₁N₁S₁I₁D₂I₁O₁U₁S₁N₁E₁S₁S₁

14 points

INSIDIOUSNESS is validvalid

the quality of being insidious [n INSIDIOUSNESSES]

181,359 of 196,601 in NWL2023·also valid in CSW24

the quality of being stealthy, cunning, or treacherous [n -ES]

121,416 of 280,887 in CSW24·also valid in NWL2023