■ adverb
1》 in a regretful manner.
2》 it is regrettable that; unfortunately.
Usage
Regretfully is used as a normal adverb to mean ‘in a regretful manner’, but it is also used as a sentence adverb meaning ‘it is regrettable that’ ( ~, mounting costs forced the branch to close ), synonymously with regrettably . Despite objections from traditionalists, this use is now well established.