Impassive

Im‐pas″sive (?), a. Not susceptible of pain or suffering; apathetic; impassible; unmoved.

Impassive as the marble in the quarry. De Quincey.

On the impassive ice the lightings play. Pope.

— Im‐pas″sive‐ly, adv. — Im‐pas″sive‐ness, n.