re ‧ gret ‧ ta ‧ bly /rɪˈɡretəbli/ BrE AmE adverb
[ Word Family: adverb : ↑ regrettably , ↑ regretfully ; adjective : ↑ regrettable , ↑ regretful ; verb : ↑ regret ; noun : ↑ regret ]
used to talk about a situation that you wish was different or that you are sorry about SYN regretfully
[sentence adverb]
Regrettably, he will not be able to come.