The word “regrettably” is an adverb that expresses sorrow, disappointment, or a sense of loss about a particular situation.
Antonyms for “regrettably” could include “fortunately” or “happily”.
“Fortunately” implies that something has happened in a positive or beneficial way, which is the opposite of the negative connotations of “regrettably”. For example, “Regrettably, the team lost the game.” In contrast, “Fortunately, they had another chance to play and won the next match.” Here, “fortunately” shows that the situation turned out well instead of being a cause for regret.
“Happily” also serves as an antonym as it indicates a state of joy or contentment. While “regrettably” brings a sense of sadness or remorse, “happily” brings a sense of pleasure and satisfaction. For instance, “Regrettably, she had to miss the party.” But, “Happily, she was able to attend a different event that was just as enjoyable.” In this case, “happily” shows a positive outcome as opposed to the regret expressed by “regrettably”.
In conclusion, words like “fortunately” and “happily” are antonyms of “regrettably” as they represent positive and desirable situations rather than the disappointment or sorrow that “regrettably” conveys.