unacceptably

Not within the limits of what is generally considered to be acceptable.

Japanese Meaning

容認できないほど / 許容の範囲外で / 受け入れがたい程度に

The board found the customer service's response times unacceptably slow, prompting an overhaul of the support department.

取締役会は顧客対応の応答時間が許容できないほど遅いと判断し、サポート部門の全面的な見直しを促した。

Sense（1）

Not within the limits of what is generally considered to be acceptable.

The levels of lead in marine hull paints are still unacceptably high.

more unacceptably

（ comparative ）

most unacceptably

（ superlative ）