Which of the following words means incapable of being erased?

The word that means incapable of being erased is "indelible." This term is often used to refer to marks, writing, or impressions that cannot be removed or forgotten. For example, indelible ink is designed to stay permanently on a surface without fading or washing away. In a broader context, indelible memories or experiences are those that leave a lasting impact and cannot be easily forgotten.

This matches the definition in the question, highlighting its permanence and resistance to removal, which is crucial for understanding the term in various contexts, such as writing, memory, or even emotional experiences. The other choices, while they may have interesting meanings, do not relate to the idea of being unable to be erased.