criminally
adv. manner B2 Upper Intermediate US //ˈkɹɪmənəɫi// UK //kɹˈɪmɪnəli// crim·i·nal·ly
adv. in a way that breaks the law, or to describe something that is very bad or unfair. You often use it to show that something good is being ignored or wasted.
adv. in a manner that involves or relates to a crime; also used figuratively to emphasize that something is extreme or neglected to a shameful degree.
The company was found to have acted criminally.
It is criminally unfair that such a talented musician has never been offered a recording contract.
The historic building was criminally neglected for decades until a local heritage group finally secured the funds necessary for its complete structural restoration.
Usage
When used figuratively for emphasis, it typically precedes an adjective like 'underrated', 'neglected', or 'expensive'.