Indelible (adjective)

1. Impossible to remove or erase.
2. Lasting for a long time and difficult to forget.
3. Making a permanent mark that cannot be removed.

Origin:

From latin indelibilis, from in- ("not") + delibare ("to effac.e")

Examples:

1. The ink used in the pen is indelible and can't be erased.
2. The memories of that day were indelible in his mind.
3. The mark on the wall was indelible and couldn't be removed.
4. The stain on the carpet was indelible and couldn't be cleaned.
5. The impact of the tragedy on the community was indelible.