Translation

ありそうもなく / 信じられないほど / 意外にも

Meaning

Occurring or existing in a way that seems unlikely, unbelievable, or contrary to what one would expect.

Examples

• The team managed to win the championship, improbably beating their rivals in the final match.
  The team managed to win the championship, improbably beating their rivals in the final match.
• He arrived at the formal dinner improbably dressed in shorts and a t-shirt.
  He arrived at the formal dinner improbably dressed in shorts and a t-shirt.