Usage notes

In careful usage, regretfully means with'' regret (in a manner expressed with regret, expressing remorse), while regrettably means ''deserving'' regret (sadly, unfortunately), and in the body of sentences this distinction is observed: regrettably/regretfully], Paul Brians, Common Errors in English Usage ''John regretfully asked for forgiveness,'' not ''*John regrettably asked for forgiveness,'' and ''The weather was regrettably terrible,'' not ''*The weather was regretfully terrible.'' These terms are occasionally conflated, a practice noted and decried since Fowler 1926 (in the forms regretful and regrettable).''Merriam-Webster's dictionary of English usage, 1994, ISBN 978-0-87779132-4, [http://books.google.com/books?id=2yJusP0vrdgC&pg=PA808&q=regretfully%20regrettably p. 808 However, in use as a (sentence adverb), these are sometimes used interchangeably to mean “unfortunately”, a practice noted since the 1960s in the United States, as in: Regrettably, it is raining'' or ''Regretfully, it is raining,'' the latter being proscribed by some. This is similar to and possibly influenced by the use of hopefully, which predates this usage of regretfully''', and is both far more popular than '''regretfully and has no precise equivalent, *''hopeably not existing.