ROGET THESAURUS
regrettably
Regret
N
regret, repining, homesickness, nostalgia, mal du pays, maladie, lamentation, penitence, bitterness, heartburning, recrimination (accusation), laudator temporis acti, regretting, regretful, homesick, regretted, much to be regretted, regrettable, lamentable,
regrettably, unfortunately, most unfortunately, Int, alas!, what a pity!, hang it!, 'tis pity, 'tis too true, sigh'd and look'd and sigh'd again, I'm sorry.