regrettable
adjective /rɪˈɡretəbl/
  /rɪˈɡretəbl/
(formal)- regrettable (that…) that you are sorry about and wish had not happened- It is regrettable that the police were not informed sooner.
- The loss of jobs is highly regrettable.
- a regrettable incident
 Extra Examples- It is highly regrettable that the delegate cannot be here in person.
- a deeply regrettable incident
- This is a most regrettable incident. Steps will be taken to ensure it cannot happen again.
 Oxford Collocations Dictionaryverbs- be
- seem
 - deeply
- extremely
- highly
- …