unforgettable
un·for·get·table
adjective
1.
impossible to forget
Origin
From un- + forget + -able or un- + forgettable.
WordNet 2.1 (Princeton University). Wiktionary (CC BY-SA). CMU Pronouncing Dictionary. WordNet 2.1 Copyright Princeton University. All rights reserved. Wiktionary content is available under the Creative Commons Attribution-ShareAlike Licence.