Answer:

allatonce

Answer	Crossword Clue
ALLATONCE	Without warning
ALLATONCE	Just like that
ALLATONCE	En masse

ALLATONCE	Out of the blue
ALLATONCE	Simultaneously
ALLATONCE	Very suddenly
ALLATONCE	Suddenly.
ALLATONCE	Suddenly
ALLATONCE	In the blink of an eye

Crossword

a puzzle consisting of a grid of squares and blanks into which words crossing vertically and horizontally are written according to clues.