The word "affectable" means capable of being influenced or affected. Its antonyms, on the other hand, are words that mean not capable of being influenced or affected, or resistant to change. These antonyms include terms like invulnerable, impervious, unresponsive, indifferent, and insusceptible. Invulnerable refers to something that is untouchable, completely immune to external influences. Impervious suggests that something is impenetrable, unable to be reached or affected. Unresponsive refers to a lack of reaction or sensitivity, while indifferent describes a lack of interest or concern. Insusceptible is similar to the other antonyms, indicating an inability to be affected or influenced.