to say the least
US /tə seɪ ðə liːst/
UK /tə seɪ ðə liːst/

1.
至少可以說, 不言而喻
used to indicate that one is understating something, or that the reality is more extreme or significant than what is being explicitly stated
:
•
The meeting was chaotic, to say the least.
會議很混亂,至少可以說。
•
His performance was disappointing, to say the least.
他的表現令人失望,至少可以說。