i Register
In some senses, lamentably is marked as archaic. Watch for register when choosing this word.
adv
Regrettably; in a manner deserving or inspiring lamentation.
Lamentably the good too die; we will all mourn his passing.
With lamentation.
[S]he […] lamentably recounted to hym all the felonyes / and iniuries done to her by ſyr Hewe Spencer […]
I loue a ballad but euen too well, if it be dolefull matter merrily ſet downe: or a very pleaſant thing indeede, and ſung lamentably.