Antonyms of adj forgettable

1 sense of forgettable

Sense 1
forgettable (vs. unforgettable) -- (easily forgotten)

unforgettable (vs. forgettable) -- (impossible to forget)
        => haunting, persistent -- (continually recurring to the mind; "haunting memories"; "the cathedral organ and the distant voices have a haunting beauty"- Claudia Cassidy)
        => memorable -- (worth remembering)
        => red-letter -- (memorable for being a special occasion; "on red-letter nights a large gathering greeted the celebrity")

Similarity of adj forgettable

1 sense of forgettable

Sense 1
forgettable (vs. unforgettable) -- (easily forgotten)
       => unmemorable -- (not worth remembering)