Answer: startling

AnswerCrossword Clue
STARTLINGFrightening.
STARTLINGFrightful.
STARTLINGShocking.
STARTLINGCausing surprise
STARTLINGScary or wondrous
STARTLINGAlarming
STARTLINGWondrous
STARTLINGUnexpected
STARTLINGAmazing
STARTLINGAstonishing
startlingVery surprising, astonishing, or remarkable
startlingSTARTLE, to frighten or surprise