impassiveness

Yet what makes the character work is the poignant impassiveness that conveys just how brutally life has hollowed him out.

Now they languish, sun seeping into feldspars and micas, into the quartzes until they quiver with pure excitation—in heat and cold, wind and stillness, through minutes and millennia— and still radiate impassiveness.

His expression is somewhere between remorse and impassiveness.

Robin's face, when she realised that the end of her mother's chemotherapy was not in fact good news, as she instantly thought, began to dissolve, but only allowed a subtle fracture in her impassiveness.

By this point, I admit, I was feeling the first twinges of annoyance with his impassiveness and growing less inclined to make allowances for it due to the fact of his being dead.