Antonyms of adj regrettable

1 sense of regrettable

Sense 1
regrettable, too bad -- (deserving regret; "regrettable remarks"; "it's regrettable that she didn't go to college"; "it's too bad he had no feeling himself for church")

INDIRECT (VIA unfortunate) -> fortunate -- (having unexpected good fortune; "other, less fortunate, children died"; "a fortunate choice")

Similarity of adj regrettable

1 sense of regrettable

Sense 1
regrettable, too bad -- (deserving regret; "regrettable remarks"; "it's regrettable that she didn't go to college"; "it's too bad he had no feeling himself for church")
       => unfortunate (vs. fortunate) -- (not favored by fortune; marked or accompanied by or resulting in ill fortune; "an unfortunate turn of events"; "an unfortunate decision"; "unfortunate investments"; "an unfortunate night for all concerned")