Forgettable (adjective)

1. Likely to be forgotten or easily forgotten.
2. Easily forgotten or not worth remembering.

Origin:

From forget (verb) meaning fail to remember, it means likely to be forgotten or easily forgotten.

Examples:

1. The movie was forgettable.
2. The party was forgettable.
3. The lecture was forgettable.
4. The book was forgettable.
5. The conversation was forgettable.