frighteningly

/F R AY1 T AH0 N IH0 NG L IY0/
adverb
  1. 1

    In a frightening or terrifying manner.

  2. 2

    Very; beyond usual expectation so as to cause surprise or concern.

    โ€œThe pitcher that was set before me was frighteningly large.โ€

Source: https://en.wiktionary.org/wiki/frighteningly